TY  - JOUR
AU  - Godoy, Cesar A.
AU  - de las Rivas, Blanca
AU  - Bezbradica, Dejan
AU  - Bolivar, Juan M.
AU  - Lopez-Gallego, Fernando
AU  - Fernandez-Lorente, Gloria
AU  - Guisan, Jose M.
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1875
AB  - Lipase from Geobacillus thermocatenulatus (BTL2) was immobilized in two different matrixes. In one derivative, the enzyme was immobilized on agarose activated with cyanogen bromide (CNBr-BTL2) via its most reactive superficial amino group, whereas the other derivative was covalently immobilized on glyoxyl agarose supports (Gx-BTL2). The latter immobilization protocol leads to intense multipoint covalent attachment between the lysine richest region of enzyme and the glyoxyl groups on the support surface. The resulted solid derivatives were unfolded by incubation under high concentrations of guanidine and then resuspended in aqueous media under different experimental conditions. In both CNBr-BTL2 and Gx-BTL2 derivatives, the oxidation of Cys residues during the unfolding/refolding processes led to inefficient folding for the enzyme because only 25-30% of its initial activity was recovered after 3 h in refolding conditions. Dithiothreitol (DTT), a very mild reducing agent, prevented Cys oxidation during the unfolding/refolding process, greatly improving activity recovery in the refolded forms. In parallel, other variables such as pH, buffer composition and the presence of polymers and other additives, had different effects on refolding efficiencies and refolding rates for both derivatives. In the case of solid derivatives of BTL2 immobilized on CNBr-agarose, the surface's chemistry was crucial to guarantee an optimal protein refolding. In this way, uncharged protein vicinities resulted in better refolding efficiencies than those charged ones.
PB  - Elsevier Science Inc, New York
T2  - Enzyme and Microbial Technology
T1  - Reactivation of a thermostable lipase by solid phase unfolding/refolding Effect of cysteine residues on refolding efficiency
EP  - 394
IS  - 4
SP  - 388
VL  - 49
DO  - 10.1016/j.enzmictec.2011.06.018
ER  - 

@article{
author = "Godoy, Cesar A. and de las Rivas, Blanca and Bezbradica, Dejan and Bolivar, Juan M. and Lopez-Gallego, Fernando and Fernandez-Lorente, Gloria and Guisan, Jose M.",
year = "2011",
abstract = "Lipase from Geobacillus thermocatenulatus (BTL2) was immobilized in two different matrixes. In one derivative, the enzyme was immobilized on agarose activated with cyanogen bromide (CNBr-BTL2) via its most reactive superficial amino group, whereas the other derivative was covalently immobilized on glyoxyl agarose supports (Gx-BTL2). The latter immobilization protocol leads to intense multipoint covalent attachment between the lysine richest region of enzyme and the glyoxyl groups on the support surface. The resulted solid derivatives were unfolded by incubation under high concentrations of guanidine and then resuspended in aqueous media under different experimental conditions. In both CNBr-BTL2 and Gx-BTL2 derivatives, the oxidation of Cys residues during the unfolding/refolding processes led to inefficient folding for the enzyme because only 25-30% of its initial activity was recovered after 3 h in refolding conditions. Dithiothreitol (DTT), a very mild reducing agent, prevented Cys oxidation during the unfolding/refolding process, greatly improving activity recovery in the refolded forms. In parallel, other variables such as pH, buffer composition and the presence of polymers and other additives, had different effects on refolding efficiencies and refolding rates for both derivatives. In the case of solid derivatives of BTL2 immobilized on CNBr-agarose, the surface's chemistry was crucial to guarantee an optimal protein refolding. In this way, uncharged protein vicinities resulted in better refolding efficiencies than those charged ones.",
publisher = "Elsevier Science Inc, New York",
journal = "Enzyme and Microbial Technology",
title = "Reactivation of a thermostable lipase by solid phase unfolding/refolding Effect of cysteine residues on refolding efficiency",
pages = "394-388",
number = "4",
volume = "49",
doi = "10.1016/j.enzmictec.2011.06.018"
}

Godoy, C. A., de las Rivas, B., Bezbradica, D., Bolivar, J. M., Lopez-Gallego, F., Fernandez-Lorente, G.,& Guisan, J. M.. (2011). Reactivation of a thermostable lipase by solid phase unfolding/refolding Effect of cysteine residues on refolding efficiency. in Enzyme and Microbial Technology
Elsevier Science Inc, New York., 49(4), 388-394.
https://doi.org/10.1016/j.enzmictec.2011.06.018

Godoy CA, de las Rivas B, Bezbradica D, Bolivar JM, Lopez-Gallego F, Fernandez-Lorente G, Guisan JM. Reactivation of a thermostable lipase by solid phase unfolding/refolding Effect of cysteine residues on refolding efficiency. in Enzyme and Microbial Technology. 2011;49(4):388-394.
doi:10.1016/j.enzmictec.2011.06.018 .

Godoy, Cesar A., de las Rivas, Blanca, Bezbradica, Dejan, Bolivar, Juan M., Lopez-Gallego, Fernando, Fernandez-Lorente, Gloria, Guisan, Jose M., "Reactivation of a thermostable lipase by solid phase unfolding/refolding Effect of cysteine residues on refolding efficiency" in Enzyme and Microbial Technology, 49, no. 4 (2011):388-394,
https://doi.org/10.1016/j.enzmictec.2011.06.018 . .

TY  - JOUR
AU  - Šaponjić, Svetlana V.
AU  - Knežević-Jugović, Zorica
AU  - Bezbradica, Dejan
AU  - Žuža, Milena
AU  - Saied, Omar Ali
AU  - Bošković-Vragolović, Nevenka
AU  - Mijin, Dušan
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1691
AB  - Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion ( gt  99%) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g(-1) dry support and in a relatively short time (24 hrs) at 37 degrees C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2% yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale.
PB  - University of Catolica De Valparaiso, Valparaiso
T2  - Electronic Journal of Biotechnology
T1  - Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study
IS  - 6
VL  - 13
DO  - 10.2225/vol13-issue6-fulltext-8
ER  - 

@article{
author = "Šaponjić, Svetlana V. and Knežević-Jugović, Zorica and Bezbradica, Dejan and Žuža, Milena and Saied, Omar Ali and Bošković-Vragolović, Nevenka and Mijin, Dušan",
year = "2010",
abstract = "Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion ( gt  99%) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g(-1) dry support and in a relatively short time (24 hrs) at 37 degrees C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2% yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale.",
publisher = "University of Catolica De Valparaiso, Valparaiso",
journal = "Electronic Journal of Biotechnology",
title = "Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study",
number = "6",
volume = "13",
doi = "10.2225/vol13-issue6-fulltext-8"
}

Šaponjić, S. V., Knežević-Jugović, Z., Bezbradica, D., Žuža, M., Saied, O. A., Bošković-Vragolović, N.,& Mijin, D.. (2010). Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study. in Electronic Journal of Biotechnology
University of Catolica De Valparaiso, Valparaiso., 13(6).
https://doi.org/10.2225/vol13-issue6-fulltext-8

Šaponjić SV, Knežević-Jugović Z, Bezbradica D, Žuža M, Saied OA, Bošković-Vragolović N, Mijin D. Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study. in Electronic Journal of Biotechnology. 2010;13(6).
doi:10.2225/vol13-issue6-fulltext-8 .

Šaponjić, Svetlana V., Knežević-Jugović, Zorica, Bezbradica, Dejan, Žuža, Milena, Saied, Omar Ali, Bošković-Vragolović, Nevenka, Mijin, Dušan, "Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study" in Electronic Journal of Biotechnology, 13, no. 6 (2010),
https://doi.org/10.2225/vol13-issue6-fulltext-8 . .

TY  - JOUR
AU  - Bradić, Milena R.
AU  - Ognjanović, Nevena
AU  - Bezbradica, Dejan
AU  - Grbavčić, Sanja
AU  - Avramović, Nataša
AU  - Mijin, Dušan
AU  - Knežević-Jugović, Zorica
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1632
AB  - Monoacylglycerols are non-ionic surfactants widely used in the food industry. They are also important in cosmetic and pharmaceutical industries as drug carriers and for consistency improvements in creams and lotions. The current process for their production is based on the glycerolysis of natural fats and oils in the presence of inorganic catalysts at temperatures higher than 220°C. The major drawbacks of this process include high-energy consumption, low yield, and poor product quality. The use of lipases for monoacylglycerols production offers environmental advantages and a reduction in energy consumption. Besides, the same surfactants prepared by the enzymatic synthesis may be labeled as 'natural'. Recent progress in the application of highly-stable lipases in the organic solvents offers the possibility of employing various methods to the enzyme-catalyzed synthesis of monoacylglycerols, such as selective hydrolysis of fats and oils using 1,3-regiospecific lipases, the esterification of glycerol with fatty acids and the glycerolysis of fats or oils. In this review, different reaction systems such as aqueous-organic two-phase systems, microemulsions and reverse micelles systems, anhydrous organic solvents, solvent-free systems with free or immobilized lipases, as well as the use of two-phase membrane reactor systems are presented. We discuss some of the key factors, such as control of water content, removal of products from reaction system, and the effects of solvent on the lipase activity and selectivity, that must be addressed in order to obtain an efficient reaction system with high yields of monoacylglycerols. Engineering of the enzymatic monoacylglycerols synthesis processes requires also optimization of other factors such as: molar ratio of substrates, temperature, type of lipase immobilization and supports (if any), reactor design and operating regime.
AB  - Monoacilgliceroli (MAG), zahvaljujući svojoj amfipatičnoj strukturi, imaju veliki značaj i primenu kao emulgatori u prehrambenoj industriji. Koriste se i u kozmetičkoj i farmaceutskoj industriji za pripremu emulzija ulje/voda (U/V) i za poboljšanje konzistencije krema i losiona. Konvencionalni hemijski postupci hidrolize masti imaju značajnih nedostataka jer se odvijaju na visokim temperaturama i pritiscima uz korišćenje neorganskih katalizatora. Pri ovako drastičnim procesnim uslovima, obrazuju se proizvodi promenjene boje i neprijatne arome, koji se moraju naknadno prečišćavati što poskupljuje proizvodnju. Enzimski postupci za dobijanje monoacilglicerola imaju značajnih prednosti, a to su pre svega blagi reakcioni uslovi, usmerenost reakcije kao i znatno manji troškovi za energiju. U ovom radu razmatrani su osnovni načini enzimskog dobijanja monoacilglicerola kao što su parcijalna hidroliza masti i ulja poziciono specifičnim lipazama, esterifikacija masnih kiselina i alkohola i gliceroliza masti i ulja, sa posebnim osvrtom na prednosti i nedostatke svakog od njih.
PB  - Association of Chemical Engineers of Serbia
T2  - Hemijska industrija
T1  - Synthesis of monoacylglycerols by enzymatic methods
T1  - Enzimska sinteza monoacilglicerola
EP  - 388
IS  - 5
SP  - 375
VL  - 64
DO  - 10.2298/HEMIND100510040B
ER  - 

@article{
author = "Bradić, Milena R. and Ognjanović, Nevena and Bezbradica, Dejan and Grbavčić, Sanja and Avramović, Nataša and Mijin, Dušan and Knežević-Jugović, Zorica",
year = "2010",
abstract = "Monoacylglycerols are non-ionic surfactants widely used in the food industry. They are also important in cosmetic and pharmaceutical industries as drug carriers and for consistency improvements in creams and lotions. The current process for their production is based on the glycerolysis of natural fats and oils in the presence of inorganic catalysts at temperatures higher than 220°C. The major drawbacks of this process include high-energy consumption, low yield, and poor product quality. The use of lipases for monoacylglycerols production offers environmental advantages and a reduction in energy consumption. Besides, the same surfactants prepared by the enzymatic synthesis may be labeled as 'natural'. Recent progress in the application of highly-stable lipases in the organic solvents offers the possibility of employing various methods to the enzyme-catalyzed synthesis of monoacylglycerols, such as selective hydrolysis of fats and oils using 1,3-regiospecific lipases, the esterification of glycerol with fatty acids and the glycerolysis of fats or oils. In this review, different reaction systems such as aqueous-organic two-phase systems, microemulsions and reverse micelles systems, anhydrous organic solvents, solvent-free systems with free or immobilized lipases, as well as the use of two-phase membrane reactor systems are presented. We discuss some of the key factors, such as control of water content, removal of products from reaction system, and the effects of solvent on the lipase activity and selectivity, that must be addressed in order to obtain an efficient reaction system with high yields of monoacylglycerols. Engineering of the enzymatic monoacylglycerols synthesis processes requires also optimization of other factors such as: molar ratio of substrates, temperature, type of lipase immobilization and supports (if any), reactor design and operating regime., Monoacilgliceroli (MAG), zahvaljujući svojoj amfipatičnoj strukturi, imaju veliki značaj i primenu kao emulgatori u prehrambenoj industriji. Koriste se i u kozmetičkoj i farmaceutskoj industriji za pripremu emulzija ulje/voda (U/V) i za poboljšanje konzistencije krema i losiona. Konvencionalni hemijski postupci hidrolize masti imaju značajnih nedostataka jer se odvijaju na visokim temperaturama i pritiscima uz korišćenje neorganskih katalizatora. Pri ovako drastičnim procesnim uslovima, obrazuju se proizvodi promenjene boje i neprijatne arome, koji se moraju naknadno prečišćavati što poskupljuje proizvodnju. Enzimski postupci za dobijanje monoacilglicerola imaju značajnih prednosti, a to su pre svega blagi reakcioni uslovi, usmerenost reakcije kao i znatno manji troškovi za energiju. U ovom radu razmatrani su osnovni načini enzimskog dobijanja monoacilglicerola kao što su parcijalna hidroliza masti i ulja poziciono specifičnim lipazama, esterifikacija masnih kiselina i alkohola i gliceroliza masti i ulja, sa posebnim osvrtom na prednosti i nedostatke svakog od njih.",
publisher = "Association of Chemical Engineers of Serbia",
journal = "Hemijska industrija",
title = "Synthesis of monoacylglycerols by enzymatic methods, Enzimska sinteza monoacilglicerola",
pages = "388-375",
number = "5",
volume = "64",
doi = "10.2298/HEMIND100510040B"
}

Bradić, M. R., Ognjanović, N., Bezbradica, D., Grbavčić, S., Avramović, N., Mijin, D.,& Knežević-Jugović, Z.. (2010). Synthesis of monoacylglycerols by enzymatic methods. in Hemijska industrija
Association of Chemical Engineers of Serbia., 64(5), 375-388.
https://doi.org/10.2298/HEMIND100510040B

Bradić MR, Ognjanović N, Bezbradica D, Grbavčić S, Avramović N, Mijin D, Knežević-Jugović Z. Synthesis of monoacylglycerols by enzymatic methods. in Hemijska industrija. 2010;64(5):375-388.
doi:10.2298/HEMIND100510040B .

Bradić, Milena R., Ognjanović, Nevena, Bezbradica, Dejan, Grbavčić, Sanja, Avramović, Nataša, Mijin, Dušan, Knežević-Jugović, Zorica, "Synthesis of monoacylglycerols by enzymatic methods" in Hemijska industrija, 64, no. 5 (2010):375-388,
https://doi.org/10.2298/HEMIND100510040B . .

TY  - JOUR
AU  - Ognjanović, Nevena
AU  - Petrović, Slobodan
AU  - Bezbradica, Dejan
AU  - Knežević-Jugović, Zorica
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1628
AB  - Lipases can be used for a variety of biotechnological applications: synthesis of fine chemicals, therapeutics, agrochemicals, cosmetics, flavors, biopolymers and biodiesel. Biodiesel is an alternative fuel for diesel engines that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short chain alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The usage of lipases has several advantages over the conventional chemical methods. It is considered as less energy intensive and environmentally friendly. However, there are two main obstacles associated with the effective utilization of lipases in the production of biodiesel. The main one is the cost of the enzyme and its poor stability in the presence of excess alcohol. Several strategies are proposed to overcome these drawbacks: immobilization of lipases, stepwise addition of alcohol, and the usage of novel acyl acceptors and the usage of whole cell biocatalysts.
AB  - Lipaze predstavljaju jednu od najvažnijih grupa biokatalizatora koji imaju veliku primenu u biotehnološkim procesima. Zahvaljujući činjenici da mogu katalizovati i hidrolizu i esterifikovanje, često se koriste u reakcijama transesterifikacije. Zbog niza prednosti koje imaju nad klasičnim katalizatorima lipaze postaju sve pogodnije za upotrebu u sintezi biodizela. U ovom radu prikazane su karakteristike lipaza koje se koriste u biotehnologiji, kao i njihova primena u sintezi biodizela.
PB  - Association of Chemical Engineers of Serbia
T2  - Hemijska industrija
T1  - Lipases as biocatalysts for biodiesel production
T1  - Lipaze kao biokatalizatori u sintezi biodizela
EP  - 8
IS  - 1
SP  - 1
VL  - 64
DO  - 10.2298/HEMIND1001001O
ER  - 

@article{
author = "Ognjanović, Nevena and Petrović, Slobodan and Bezbradica, Dejan and Knežević-Jugović, Zorica",
year = "2010",
abstract = "Lipases can be used for a variety of biotechnological applications: synthesis of fine chemicals, therapeutics, agrochemicals, cosmetics, flavors, biopolymers and biodiesel. Biodiesel is an alternative fuel for diesel engines that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short chain alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The usage of lipases has several advantages over the conventional chemical methods. It is considered as less energy intensive and environmentally friendly. However, there are two main obstacles associated with the effective utilization of lipases in the production of biodiesel. The main one is the cost of the enzyme and its poor stability in the presence of excess alcohol. Several strategies are proposed to overcome these drawbacks: immobilization of lipases, stepwise addition of alcohol, and the usage of novel acyl acceptors and the usage of whole cell biocatalysts., Lipaze predstavljaju jednu od najvažnijih grupa biokatalizatora koji imaju veliku primenu u biotehnološkim procesima. Zahvaljujući činjenici da mogu katalizovati i hidrolizu i esterifikovanje, često se koriste u reakcijama transesterifikacije. Zbog niza prednosti koje imaju nad klasičnim katalizatorima lipaze postaju sve pogodnije za upotrebu u sintezi biodizela. U ovom radu prikazane su karakteristike lipaza koje se koriste u biotehnologiji, kao i njihova primena u sintezi biodizela.",
publisher = "Association of Chemical Engineers of Serbia",
journal = "Hemijska industrija",
title = "Lipases as biocatalysts for biodiesel production, Lipaze kao biokatalizatori u sintezi biodizela",
pages = "8-1",
number = "1",
volume = "64",
doi = "10.2298/HEMIND1001001O"
}

Ognjanović, N., Petrović, S., Bezbradica, D.,& Knežević-Jugović, Z.. (2010). Lipases as biocatalysts for biodiesel production. in Hemijska industrija
Association of Chemical Engineers of Serbia., 64(1), 1-8.
https://doi.org/10.2298/HEMIND1001001O

Ognjanović N, Petrović S, Bezbradica D, Knežević-Jugović Z. Lipases as biocatalysts for biodiesel production. in Hemijska industrija. 2010;64(1):1-8.
doi:10.2298/HEMIND1001001O .

Ognjanović, Nevena, Petrović, Slobodan, Bezbradica, Dejan, Knežević-Jugović, Zorica, "Lipases as biocatalysts for biodiesel production" in Hemijska industrija, 64, no. 1 (2010):1-8,
https://doi.org/10.2298/HEMIND1001001O . .

TY  - JOUR
AU  - Prlainović, Nevena
AU  - Bezbradica, Dejan
AU  - Knežević-Jugović, Zorica
AU  - Kozlowska, Roksana T.
AU  - Mijin, Dušan
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1563
AB  - The synthesis of 4,6-dimethyl-3-cyano-2-pyridone was studied in a reaction catalyzed with Candida rugosa lipase. A response surface methodology (RSM) was applied for the optimization of the experimental conditions. The study showed that temperature and molar ratio cyanoacetamide/acetylacetone have a great influence on the yield of the reaction; the maximum yield was achieved at 44 degrees C with a molar ratio cyanoacetamide/acetylacetone of 36. The kinetics of the enzymatic synthesis of 4,6-dimethyl-3-cyano-2-pyridone was investigated, and it was determined that a ping-pong bi-ter mechanism with cyanoacetamide inhibition fits the obtained results. The mechanism of lipase-catalyzed reaction was proposed.
PB  - Sociedade Brasileira de Química
T2  - Journal of the Brazilian Chemical Society
T1  - A Kinetic Study of Candida rugosa Lipase-Catalyzed Synthesis of 4,6-Dimethyl-3-cyano-2-pyridone
EP  - 2293
IS  - 12
SP  - 2285
VL  - 21
UR  - https://hdl.handle.net/21.15107/rcub_technorep_1563
ER  - 

@article{
author = "Prlainović, Nevena and Bezbradica, Dejan and Knežević-Jugović, Zorica and Kozlowska, Roksana T. and Mijin, Dušan",
year = "2010",
abstract = "The synthesis of 4,6-dimethyl-3-cyano-2-pyridone was studied in a reaction catalyzed with Candida rugosa lipase. A response surface methodology (RSM) was applied for the optimization of the experimental conditions. The study showed that temperature and molar ratio cyanoacetamide/acetylacetone have a great influence on the yield of the reaction; the maximum yield was achieved at 44 degrees C with a molar ratio cyanoacetamide/acetylacetone of 36. The kinetics of the enzymatic synthesis of 4,6-dimethyl-3-cyano-2-pyridone was investigated, and it was determined that a ping-pong bi-ter mechanism with cyanoacetamide inhibition fits the obtained results. The mechanism of lipase-catalyzed reaction was proposed.",
publisher = "Sociedade Brasileira de Química",
journal = "Journal of the Brazilian Chemical Society",
title = "A Kinetic Study of Candida rugosa Lipase-Catalyzed Synthesis of 4,6-Dimethyl-3-cyano-2-pyridone",
pages = "2293-2285",
number = "12",
volume = "21",
url = "https://hdl.handle.net/21.15107/rcub_technorep_1563"
}

Prlainović, N., Bezbradica, D., Knežević-Jugović, Z., Kozlowska, R. T.,& Mijin, D.. (2010). A Kinetic Study of Candida rugosa Lipase-Catalyzed Synthesis of 4,6-Dimethyl-3-cyano-2-pyridone. in Journal of the Brazilian Chemical Society
Sociedade Brasileira de Química., 21(12), 2285-2293.
https://hdl.handle.net/21.15107/rcub_technorep_1563

Prlainović N, Bezbradica D, Knežević-Jugović Z, Kozlowska RT, Mijin D. A Kinetic Study of Candida rugosa Lipase-Catalyzed Synthesis of 4,6-Dimethyl-3-cyano-2-pyridone. in Journal of the Brazilian Chemical Society. 2010;21(12):2285-2293.
https://hdl.handle.net/21.15107/rcub_technorep_1563 .

Prlainović, Nevena, Bezbradica, Dejan, Knežević-Jugović, Zorica, Kozlowska, Roksana T., Mijin, Dušan, "A Kinetic Study of Candida rugosa Lipase-Catalyzed Synthesis of 4,6-Dimethyl-3-cyano-2-pyridone" in Journal of the Brazilian Chemical Society, 21, no. 12 (2010):2285-2293,
https://hdl.handle.net/21.15107/rcub_technorep_1563 .

TY  - JOUR
AU  - Ognjanović, Nevena
AU  - Bezbradica, Dejan
AU  - Knežević-Jugović, Zorica
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1431
AB  - The feasibility of using the commercial immobilized lipase from Candida antarctica (Novozyme 435) to synthesize biodiesel from sunflower oil in a solvent-free system has been proved. Using methanol as an acyl acceptor and the response surface methodology as an optimization technique, the optimal conditions for the transesterification has been found to be: 45 degrees C, 3% of enzyme based on oil weight, 3:1 methanol to oil molar ratio and with no added water in the system. Under these conditions,  gt 99% of oil conversion to fatty acid methyl ester (FAME) has been achieved after 50 h of reaction, but the activity of the immobilized lipase decreased markedly over the course of repeated runs. In order to improve the enzyme stability, several alternative acyl acceptors have been tested for biodiesel production under solvent-free conditions. The use of methyl acetate seems to be of great interest, resulting in high FAME yield (95.65%) and increasing the half-life of the immobilized lipase by about 20.1 times as compared to methanol. The reaction has also been verified in the industrially feasible reaction system including both a batch stirred tank reactor and a packed bed reactor. Although satisfactory performance in the batch stirred tank reactor has been achieved, the kinetics in a packed bed reactor system seems to have a slightly better profile (93.6 +/- 3.75% FAME yield after 8-10 h), corresponding to the volumetric productivity of 48.5 g/(dm(3) h). The packed bed reactor has operated for up to 72 h with almost no loss in productivity, implying that the proposed process and the immobilized system could provide a promising solution for the biodiesel synthesis at the industrial scale.
PB  - Elsevier Sci Ltd, Oxford
T2  - Bioresource Technology
T1  - Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: Process optimization and the immobilized system stability
EP  - 5154
IS  - 21
SP  - 5146
VL  - 100
DO  - 10.1016/j.biortech.2009.05.068
ER  - 

@article{
author = "Ognjanović, Nevena and Bezbradica, Dejan and Knežević-Jugović, Zorica",
year = "2009",
abstract = "The feasibility of using the commercial immobilized lipase from Candida antarctica (Novozyme 435) to synthesize biodiesel from sunflower oil in a solvent-free system has been proved. Using methanol as an acyl acceptor and the response surface methodology as an optimization technique, the optimal conditions for the transesterification has been found to be: 45 degrees C, 3% of enzyme based on oil weight, 3:1 methanol to oil molar ratio and with no added water in the system. Under these conditions,  gt 99% of oil conversion to fatty acid methyl ester (FAME) has been achieved after 50 h of reaction, but the activity of the immobilized lipase decreased markedly over the course of repeated runs. In order to improve the enzyme stability, several alternative acyl acceptors have been tested for biodiesel production under solvent-free conditions. The use of methyl acetate seems to be of great interest, resulting in high FAME yield (95.65%) and increasing the half-life of the immobilized lipase by about 20.1 times as compared to methanol. The reaction has also been verified in the industrially feasible reaction system including both a batch stirred tank reactor and a packed bed reactor. Although satisfactory performance in the batch stirred tank reactor has been achieved, the kinetics in a packed bed reactor system seems to have a slightly better profile (93.6 +/- 3.75% FAME yield after 8-10 h), corresponding to the volumetric productivity of 48.5 g/(dm(3) h). The packed bed reactor has operated for up to 72 h with almost no loss in productivity, implying that the proposed process and the immobilized system could provide a promising solution for the biodiesel synthesis at the industrial scale.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Bioresource Technology",
title = "Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: Process optimization and the immobilized system stability",
pages = "5154-5146",
number = "21",
volume = "100",
doi = "10.1016/j.biortech.2009.05.068"
}

Ognjanović, N., Bezbradica, D.,& Knežević-Jugović, Z.. (2009). Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: Process optimization and the immobilized system stability. in Bioresource Technology
Elsevier Sci Ltd, Oxford., 100(21), 5146-5154.
https://doi.org/10.1016/j.biortech.2009.05.068

Ognjanović N, Bezbradica D, Knežević-Jugović Z. Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: Process optimization and the immobilized system stability. in Bioresource Technology. 2009;100(21):5146-5154.
doi:10.1016/j.biortech.2009.05.068 .

Ognjanović, Nevena, Bezbradica, Dejan, Knežević-Jugović, Zorica, "Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: Process optimization and the immobilized system stability" in Bioresource Technology, 100, no. 21 (2009):5146-5154,
https://doi.org/10.1016/j.biortech.2009.05.068 . .

TY  - JOUR
AU  - Žuža, Milena
AU  - Milosavić, Nenad
AU  - Knežević-Jugović, Zorica
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1447
AB  - An approach to stable covalent immobilization of chemically modified penicillin G acylase from Escherichia coli on Sepabeads(R) carriers with high retention of hydrolytic activity and thermal stability is presented. The two amino-activated polymethacrylate particulate polymers with different spacer lengths used in the study were Sepabeads(R) EC EA and Sepabeads(R) EC HA. The enzyme was first modified by cross-linking with polyaldehyde derivatives of starch in order to provide it with new useful functions. Such modified enzyme was then covalently immobilized on amino supports. The method seems to provide a possibility to couple the enzyme without risking a reaction at the active site which might cause the loss of activity. Performances of these immobilized biocatalysts were compared with those obtained by the conventional method with respect to activity and thermal stability. The thermal stability study shows that starch-PGA immobilized on Sepabeads EC-EA was almost 4.5-fold more stable than the conventionally immobilized one and 7-fold more stable than free non-modified PGA. Similarly, starch-PGA immobilized on Sepabeads EC-HA was around 1.5-fold more stable than the conventionally immobilized one and almost 9.5-fold more stable than free non-modified enzyme.
PB  - Versita, Warsaw
T2  - Chemical Papers
T1  - Immobilization of modified penicillin G acylase on Sepabeads carriers
EP  - 124
IS  - 2
SP  - 117
VL  - 63
DO  - 10.2478/s11696-009-0012-z
ER  - 

@article{
author = "Žuža, Milena and Milosavić, Nenad and Knežević-Jugović, Zorica",
year = "2009",
abstract = "An approach to stable covalent immobilization of chemically modified penicillin G acylase from Escherichia coli on Sepabeads(R) carriers with high retention of hydrolytic activity and thermal stability is presented. The two amino-activated polymethacrylate particulate polymers with different spacer lengths used in the study were Sepabeads(R) EC EA and Sepabeads(R) EC HA. The enzyme was first modified by cross-linking with polyaldehyde derivatives of starch in order to provide it with new useful functions. Such modified enzyme was then covalently immobilized on amino supports. The method seems to provide a possibility to couple the enzyme without risking a reaction at the active site which might cause the loss of activity. Performances of these immobilized biocatalysts were compared with those obtained by the conventional method with respect to activity and thermal stability. The thermal stability study shows that starch-PGA immobilized on Sepabeads EC-EA was almost 4.5-fold more stable than the conventionally immobilized one and 7-fold more stable than free non-modified PGA. Similarly, starch-PGA immobilized on Sepabeads EC-HA was around 1.5-fold more stable than the conventionally immobilized one and almost 9.5-fold more stable than free non-modified enzyme.",
publisher = "Versita, Warsaw",
journal = "Chemical Papers",
title = "Immobilization of modified penicillin G acylase on Sepabeads carriers",
pages = "124-117",
number = "2",
volume = "63",
doi = "10.2478/s11696-009-0012-z"
}

Žuža, M., Milosavić, N.,& Knežević-Jugović, Z.. (2009). Immobilization of modified penicillin G acylase on Sepabeads carriers. in Chemical Papers
Versita, Warsaw., 63(2), 117-124.
https://doi.org/10.2478/s11696-009-0012-z

Žuža M, Milosavić N, Knežević-Jugović Z. Immobilization of modified penicillin G acylase on Sepabeads carriers. in Chemical Papers. 2009;63(2):117-124.
doi:10.2478/s11696-009-0012-z .

Žuža, Milena, Milosavić, Nenad, Knežević-Jugović, Zorica, "Immobilization of modified penicillin G acylase on Sepabeads carriers" in Chemical Papers, 63, no. 2 (2009):117-124,
https://doi.org/10.2478/s11696-009-0012-z . .

TY  - JOUR
AU  - Vučijak, Nevena Ž.
AU  - Petrović, Slobodan
AU  - Bezbradica, Dejan
AU  - Knežević-Jugović, Zorica
AU  - Mijin, Dušan
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1377
AB  - The importance of vitamin B6 has been known since its discovery in the 1940's. Chemical tests, elestrometric titration determinations, and absorption spectrum studies showed that this vitamin exists in three major chemical forms: pyridoxine (an alcohol), pyridoxal (an aldehyde), and pyridoxamine (a primary amine). Vitamin B6 is needed for more than 100 enzymes involved in protein metabolism, and it is assumed that this vitamin is cofactor of metabolic processes more important than any other substance. A deficiency of vitamin B6 in the human diet leads to severe disorders. Vitamin B6 is necessary for the proper function of the immune and nervous system, and helps the body convert protein to energy. This paper describes the history, properties and applications of vitamin B6, elucidation of chemical structure, and different procedures for synthesis of pyridoxine and pyridoxamine.
AB  - Vitamin B6 poznat je već 70 godina. Pod nazivom B6 podrazumeva se grupa jedinjenja, i to piridoksin, piridoksal i piridoksamin. U radu su prikazane karakteristike i primena vitamina B6, a zatim i način na koji je dokazana struktura piridoksina. U nastavku su prikazani različiti postupci dobijanja piridoksina i piridoksamina.
PB  - Association of Chemical Engineers of Serbia
T2  - Hemijska industrija
T1  - Synthesis of B6 vitamin
T1  - Sinteza vitamina B6
EP  - 360
IS  - 4
SP  - 353
VL  - 63
DO  - 10.2298/HEMIND0904353V
ER  - 

@article{
author = "Vučijak, Nevena Ž. and Petrović, Slobodan and Bezbradica, Dejan and Knežević-Jugović, Zorica and Mijin, Dušan",
year = "2009",
abstract = "The importance of vitamin B6 has been known since its discovery in the 1940's. Chemical tests, elestrometric titration determinations, and absorption spectrum studies showed that this vitamin exists in three major chemical forms: pyridoxine (an alcohol), pyridoxal (an aldehyde), and pyridoxamine (a primary amine). Vitamin B6 is needed for more than 100 enzymes involved in protein metabolism, and it is assumed that this vitamin is cofactor of metabolic processes more important than any other substance. A deficiency of vitamin B6 in the human diet leads to severe disorders. Vitamin B6 is necessary for the proper function of the immune and nervous system, and helps the body convert protein to energy. This paper describes the history, properties and applications of vitamin B6, elucidation of chemical structure, and different procedures for synthesis of pyridoxine and pyridoxamine., Vitamin B6 poznat je već 70 godina. Pod nazivom B6 podrazumeva se grupa jedinjenja, i to piridoksin, piridoksal i piridoksamin. U radu su prikazane karakteristike i primena vitamina B6, a zatim i način na koji je dokazana struktura piridoksina. U nastavku su prikazani različiti postupci dobijanja piridoksina i piridoksamina.",
publisher = "Association of Chemical Engineers of Serbia",
journal = "Hemijska industrija",
title = "Synthesis of B6 vitamin, Sinteza vitamina B6",
pages = "360-353",
number = "4",
volume = "63",
doi = "10.2298/HEMIND0904353V"
}

Vučijak, N. Ž., Petrović, S., Bezbradica, D., Knežević-Jugović, Z.,& Mijin, D.. (2009). Synthesis of B6 vitamin. in Hemijska industrija
Association of Chemical Engineers of Serbia., 63(4), 353-360.
https://doi.org/10.2298/HEMIND0904353V

Vučijak NŽ, Petrović S, Bezbradica D, Knežević-Jugović Z, Mijin D. Synthesis of B6 vitamin. in Hemijska industrija. 2009;63(4):353-360.
doi:10.2298/HEMIND0904353V .

Vučijak, Nevena Ž., Petrović, Slobodan, Bezbradica, Dejan, Knežević-Jugović, Zorica, Mijin, Dušan, "Synthesis of B6 vitamin" in Hemijska industrija, 63, no. 4 (2009):353-360,
https://doi.org/10.2298/HEMIND0904353V . .

TY  - JOUR
AU  - Grbavčić, Sanja
AU  - Bezbradica, Dejan
AU  - Karadžić, Ivanka
AU  - Knežević-Jugović, Zorica
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1405
AB  - Enzymes produced by indigenous Pseudomonas aeruginosa strain have been subjected to research considering their potential application as detergent additives. As previously noted, lipase produced by Pseudomonas aeruginosa is highly alkaline, thermostable and solvent tolerant. Furthermore, same strain exhibits both lipase and protease activity establishing this lipase as potentially desirable component of enzyme-containing detergents. Further research was carried out to investigate insusceptibility of this lipase against coexisting native protease, several commercial surfactants, oxidizing agents and commercial detergents. Lipases and proteases remained highly active when incubated with several different surfactants and oxidizing agents under washing conditions. Moreover, presence of surfactants and oxidizing agents such as Tween® 20 and Triton® X-100 initially augment lipase and protease activity. Additionally, crude lipase preparation was insusceptible to coexisting native protease hence indicating possible storage stability. Overall, the remarkable properties of these enzymes make them potential detergent additives.
AB  - Enzimi iz ekstremofilne Pseudomonas aeruginosa vrste pokazuju visoku stabilnost u alkalnoj sredini što ih čini pogodnim za primenu u proizvodnji deterdženata. U ovom radu ispitana je aktivnost lipaza i proteaza dobijenih iz ove vrste u uslovima od značaja za industriju deterdženata. Ustanovljeno je da u realnim uslovima pranja, oba enzima zadržavaju visoku aktivnost u prisustvu različitih površinski aktivnih materija i oksidacionih agenasa. Takođe, prisustvo nekih aditiva kao što su Tween® 20, Triton® X-100, SDS i NaClO u početnoj fazi povećava lipolitičku aktivnost dok je povećanje proteolitičke aktivnosti primećeno u formulacijama koje sadrže Tween® 20 i Triton® X-100. Nadalje, sama lipaza je očuvala aktivnost u prisustvu nativnih proteaza što upućuje na zaključak da bi ovi enzimi zadržali visoku efikasnost u formulacijama deterdženata i tokom procesa pranja/čišćenja.
PB  - Association of Chemical Engineers of Serbia
T2  - Hemijska industrija
T1  - Lipases and proteases produced by indigenous Pseudomonas aeruginosa strain as potential detergent additives
T1  - Lipaze i proteaze dobijene iz ekstremofilne Pseudomonas aeruginosa vrste kao aditivi u formulacijama deterdženata
EP  - 335
IS  - 4
SP  - 331
VL  - 63
DO  - 10.2298/HEMIND0904331G
ER  - 

@article{
author = "Grbavčić, Sanja and Bezbradica, Dejan and Karadžić, Ivanka and Knežević-Jugović, Zorica",
year = "2009",
abstract = "Enzymes produced by indigenous Pseudomonas aeruginosa strain have been subjected to research considering their potential application as detergent additives. As previously noted, lipase produced by Pseudomonas aeruginosa is highly alkaline, thermostable and solvent tolerant. Furthermore, same strain exhibits both lipase and protease activity establishing this lipase as potentially desirable component of enzyme-containing detergents. Further research was carried out to investigate insusceptibility of this lipase against coexisting native protease, several commercial surfactants, oxidizing agents and commercial detergents. Lipases and proteases remained highly active when incubated with several different surfactants and oxidizing agents under washing conditions. Moreover, presence of surfactants and oxidizing agents such as Tween® 20 and Triton® X-100 initially augment lipase and protease activity. Additionally, crude lipase preparation was insusceptible to coexisting native protease hence indicating possible storage stability. Overall, the remarkable properties of these enzymes make them potential detergent additives., Enzimi iz ekstremofilne Pseudomonas aeruginosa vrste pokazuju visoku stabilnost u alkalnoj sredini što ih čini pogodnim za primenu u proizvodnji deterdženata. U ovom radu ispitana je aktivnost lipaza i proteaza dobijenih iz ove vrste u uslovima od značaja za industriju deterdženata. Ustanovljeno je da u realnim uslovima pranja, oba enzima zadržavaju visoku aktivnost u prisustvu različitih površinski aktivnih materija i oksidacionih agenasa. Takođe, prisustvo nekih aditiva kao što su Tween® 20, Triton® X-100, SDS i NaClO u početnoj fazi povećava lipolitičku aktivnost dok je povećanje proteolitičke aktivnosti primećeno u formulacijama koje sadrže Tween® 20 i Triton® X-100. Nadalje, sama lipaza je očuvala aktivnost u prisustvu nativnih proteaza što upućuje na zaključak da bi ovi enzimi zadržali visoku efikasnost u formulacijama deterdženata i tokom procesa pranja/čišćenja.",
publisher = "Association of Chemical Engineers of Serbia",
journal = "Hemijska industrija",
title = "Lipases and proteases produced by indigenous Pseudomonas aeruginosa strain as potential detergent additives, Lipaze i proteaze dobijene iz ekstremofilne Pseudomonas aeruginosa vrste kao aditivi u formulacijama deterdženata",
pages = "335-331",
number = "4",
volume = "63",
doi = "10.2298/HEMIND0904331G"
}

Grbavčić, S., Bezbradica, D., Karadžić, I.,& Knežević-Jugović, Z.. (2009). Lipases and proteases produced by indigenous Pseudomonas aeruginosa strain as potential detergent additives. in Hemijska industrija
Association of Chemical Engineers of Serbia., 63(4), 331-335.
https://doi.org/10.2298/HEMIND0904331G

Grbavčić S, Bezbradica D, Karadžić I, Knežević-Jugović Z. Lipases and proteases produced by indigenous Pseudomonas aeruginosa strain as potential detergent additives. in Hemijska industrija. 2009;63(4):331-335.
doi:10.2298/HEMIND0904331G .

Grbavčić, Sanja, Bezbradica, Dejan, Karadžić, Ivanka, Knežević-Jugović, Zorica, "Lipases and proteases produced by indigenous Pseudomonas aeruginosa strain as potential detergent additives" in Hemijska industrija, 63, no. 4 (2009):331-335,
https://doi.org/10.2298/HEMIND0904331G . .

TY  - JOUR
AU  - Bezbradica, Dejan
AU  - Mijin, Dušan
AU  - Mihailović, Mladen
AU  - Knežević-Jugović, Zorica
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1455
AB  - BACKGROUND: Immobilization of lipase (triacylglycerol acylhydrolase EC 3.1.1.3) from Candida rugosa on Eupergite (R) C and Eupergit (R) C 250L was performed under microwave irradiation in order to reduce immobilization time. Lipase loading, hydrolytic activity, esterification activity and operational stability in organic solvent of immobilized lipase preparation were determined. RESULTS: The microwave-assisted procedure resulted in a 29% lower lipase loadings, compared with immobilized lipase obtained without microwaves. In hydrolytic activity assay, lipase immobilized under microwaves exhibited a 23% higher specific activity. Slight activation of lipase by microwave-assisted immobilization was observed, since specific activity was around 5% higher than for free lipase. Lipase of highest activity was obtained after 2 min immobilization on Eupergit (R) C. The same preparation exhibited high esterification activity in organic medium and a half life of 212 h was determined in multiple use assay. CONCLUSION: The application of microwave irradiation leads to reduction of immobilization time from 2 days to only 2 min. The immobilized lipase obtained has prospects for further application due to its high retained activity and stability.
PB  - Wiley, Hoboken
T2  - Journal of Chemical Technology and Biotechnology
T1  - Microwave-assisted immobilization of lipase from Candida rugosa on Eupergit (R) supports
EP  - 1648
IS  - 11
SP  - 1642
VL  - 84
DO  - 10.1002/jctb.2222
ER  - 

@article{
author = "Bezbradica, Dejan and Mijin, Dušan and Mihailović, Mladen and Knežević-Jugović, Zorica",
year = "2009",
abstract = "BACKGROUND: Immobilization of lipase (triacylglycerol acylhydrolase EC 3.1.1.3) from Candida rugosa on Eupergite (R) C and Eupergit (R) C 250L was performed under microwave irradiation in order to reduce immobilization time. Lipase loading, hydrolytic activity, esterification activity and operational stability in organic solvent of immobilized lipase preparation were determined. RESULTS: The microwave-assisted procedure resulted in a 29% lower lipase loadings, compared with immobilized lipase obtained without microwaves. In hydrolytic activity assay, lipase immobilized under microwaves exhibited a 23% higher specific activity. Slight activation of lipase by microwave-assisted immobilization was observed, since specific activity was around 5% higher than for free lipase. Lipase of highest activity was obtained after 2 min immobilization on Eupergit (R) C. The same preparation exhibited high esterification activity in organic medium and a half life of 212 h was determined in multiple use assay. CONCLUSION: The application of microwave irradiation leads to reduction of immobilization time from 2 days to only 2 min. The immobilized lipase obtained has prospects for further application due to its high retained activity and stability.",
publisher = "Wiley, Hoboken",
journal = "Journal of Chemical Technology and Biotechnology",
title = "Microwave-assisted immobilization of lipase from Candida rugosa on Eupergit (R) supports",
pages = "1648-1642",
number = "11",
volume = "84",
doi = "10.1002/jctb.2222"
}

Bezbradica, D., Mijin, D., Mihailović, M.,& Knežević-Jugović, Z.. (2009). Microwave-assisted immobilization of lipase from Candida rugosa on Eupergit (R) supports. in Journal of Chemical Technology and Biotechnology
Wiley, Hoboken., 84(11), 1642-1648.
https://doi.org/10.1002/jctb.2222

Bezbradica D, Mijin D, Mihailović M, Knežević-Jugović Z. Microwave-assisted immobilization of lipase from Candida rugosa on Eupergit (R) supports. in Journal of Chemical Technology and Biotechnology. 2009;84(11):1642-1648.
doi:10.1002/jctb.2222 .

Bezbradica, Dejan, Mijin, Dušan, Mihailović, Mladen, Knežević-Jugović, Zorica, "Microwave-assisted immobilization of lipase from Candida rugosa on Eupergit (R) supports" in Journal of Chemical Technology and Biotechnology, 84, no. 11 (2009):1642-1648,
https://doi.org/10.1002/jctb.2222 . .

TY  - JOUR
AU  - Ognjanović, Nevena
AU  - Šaponjić, Svetlana V.
AU  - Bezbradica, Dejan
AU  - Knežević, Zorica
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1279
AB  - Biodiesel is an alternative fuel for diesel engine that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The aim of the present work was to investigate novel acyl acceptors for biodiesel production. 2-Propanol and n-butanol have a less negative effect on lipase stability, and they also improve low temperature properties of the fuel. However, excess alcohol leads to inactivation of the enzyme, and glycerol, a major byproduct, can block the immobilized enzyme, resulting in low enzymatic activity. This problem was solved by using methyl acetate as acyl acceptor. Triacetylglycerol is produced instead of glycerol, and it has no negative effect on the activity of the lipase.
AB  - U ovom radu ispitana je mogućnost primene različitih acil akceptora kao polaznih reaktanata umesto metanola u sintezi biodizela u cilju smanjenja inhibicije enzima, povećanja njegove stabilnosti i mogućnosti značajnog pojednostavljivanja izvođenja procesa. Prvo je ispitana mogućnost korišćenja različitih alkohola: 2-propanol i n-butanol koji imaju manji uticaj na denaturaciju enzima. Osim toga, primenom ovih alkohola dobija se gorivo boljeg kvaliteta, pošto se sa povećanjem broja ugljenikovih atoma povećava oktanski broj, temperatura paljenja, kao i sadržaj toplote. Drugi deo istraživanja bio je orijentisan ka ispitivanju mogućnosti korišćenja metilacetata kao pogodnog nukleofila. Za razliku od alkohola, primenom ovog acil akceptora omogućen je jednostepeni postupak sinteze biodizela, što značajno smanjuje vreme trajanja reakcije, kao i kompleksnost iste. Takođe, primenom metilacetata povećava se stabilnost biokatalizatora, što omogućava višekratnu upotrebu. Naime, u reakciji sa metilacetatom kao nusprodukt se ne stvara glicerol već triacetilglicerol, koji nema negativan efekat na stabilnost lipaze.
PB  - Faculty of Technology, Novi Sad
T2  - Acta periodica technologica
T1  - Lipase-catalyzed biodiesel synthesis with different acyl acceptors
T1  - Primena novih acil akceptora u procesu enzimski katalizovane sinteze biodizela
EP  - 169
IS  - 39
SP  - 161
DO  - 10.2298/APT0839161O
ER  - 

@article{
author = "Ognjanović, Nevena and Šaponjić, Svetlana V. and Bezbradica, Dejan and Knežević, Zorica",
year = "2008",
abstract = "Biodiesel is an alternative fuel for diesel engine that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The aim of the present work was to investigate novel acyl acceptors for biodiesel production. 2-Propanol and n-butanol have a less negative effect on lipase stability, and they also improve low temperature properties of the fuel. However, excess alcohol leads to inactivation of the enzyme, and glycerol, a major byproduct, can block the immobilized enzyme, resulting in low enzymatic activity. This problem was solved by using methyl acetate as acyl acceptor. Triacetylglycerol is produced instead of glycerol, and it has no negative effect on the activity of the lipase., U ovom radu ispitana je mogućnost primene različitih acil akceptora kao polaznih reaktanata umesto metanola u sintezi biodizela u cilju smanjenja inhibicije enzima, povećanja njegove stabilnosti i mogućnosti značajnog pojednostavljivanja izvođenja procesa. Prvo je ispitana mogućnost korišćenja različitih alkohola: 2-propanol i n-butanol koji imaju manji uticaj na denaturaciju enzima. Osim toga, primenom ovih alkohola dobija se gorivo boljeg kvaliteta, pošto se sa povećanjem broja ugljenikovih atoma povećava oktanski broj, temperatura paljenja, kao i sadržaj toplote. Drugi deo istraživanja bio je orijentisan ka ispitivanju mogućnosti korišćenja metilacetata kao pogodnog nukleofila. Za razliku od alkohola, primenom ovog acil akceptora omogućen je jednostepeni postupak sinteze biodizela, što značajno smanjuje vreme trajanja reakcije, kao i kompleksnost iste. Takođe, primenom metilacetata povećava se stabilnost biokatalizatora, što omogućava višekratnu upotrebu. Naime, u reakciji sa metilacetatom kao nusprodukt se ne stvara glicerol već triacetilglicerol, koji nema negativan efekat na stabilnost lipaze.",
publisher = "Faculty of Technology, Novi Sad",
journal = "Acta periodica technologica",
title = "Lipase-catalyzed biodiesel synthesis with different acyl acceptors, Primena novih acil akceptora u procesu enzimski katalizovane sinteze biodizela",
pages = "169-161",
number = "39",
doi = "10.2298/APT0839161O"
}

Ognjanović, N., Šaponjić, S. V., Bezbradica, D.,& Knežević, Z.. (2008). Lipase-catalyzed biodiesel synthesis with different acyl acceptors. in Acta periodica technologica
Faculty of Technology, Novi Sad.(39), 161-169.
https://doi.org/10.2298/APT0839161O

Ognjanović N, Šaponjić SV, Bezbradica D, Knežević Z. Lipase-catalyzed biodiesel synthesis with different acyl acceptors. in Acta periodica technologica. 2008;(39):161-169.
doi:10.2298/APT0839161O .

Ognjanović, Nevena, Šaponjić, Svetlana V., Bezbradica, Dejan, Knežević, Zorica, "Lipase-catalyzed biodiesel synthesis with different acyl acceptors" in Acta periodica technologica, no. 39 (2008):161-169,
https://doi.org/10.2298/APT0839161O . .

TY  - JOUR
AU  - Knežević-Jugović, Zorica
AU  - Bezbradica, Dejan
AU  - Jakovljević, Živana
AU  - Dimitrijević-Branković, Suzana
AU  - Mijin, Dušan
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1304
AB  - In this study, the synthesis of pentyl 2-methylpropanoate employing a commercial lipase from Candida rugosa was investigated, the emphasis being placed on analyzing the effects of various process conditions on the yield of ester. The response surface methodology (RSM) and five-level-five-factor central composite rotatable design (CCRD) were used to evaluate the effects of variables, namely the initial water content, 0.0-2.0% (w/v), the reaction temperature, 35-75°C, the enzyme concentration, 1.0-5.0 g dm-3, the acid/alcohol mole ratio, 1:2-5:2, and the reaction time, 4-48 h, on the yield (%) of ester. The production of pentyl 2-methylpropanoate was optimized and an ester yield response equation was obtained, enabling the prediction of ester yields from known values of the five main factors. It seems that the enzyme concentration, reaction time and acid/alcohol mole ratio predominantly determine the conversion process, while the amount of added water amount had no significant influence on the ester yield. Conversion of around 92 % of the substrate to ester could be realized using a concentration of lipase as low as 4.0 g dm-3 and in a relatively short time (26 h) at 35°C, when a high substrate mole ratio of 2.5 was used.
AB  - U radu su ispitani uticaji različitih procesnih parametara na sintezu pentil-2-metilpropanoata katalizovanu lipazom iz Candida rugosa. U cilju optimizacije enzimske sinteze estara primenjena je metodologija odzivnih površina u skladu sa odabranim centralnim kompozicionim rotabilnim planom (pet faktora na pet nivoa). Ispitani su uticaji procesnih parametara na prinos estra u sledećim intervalima: početnog sadržaja vode (0,0-2,0 %), temperature (35-75°C), koncentracije enzima (1,0-5,0 g dm-3), početnog molskog udela supstrata (1:2-5:2) i reakcionog vremena (4-48 h). Dobijen je adekvatan matematički model na osnovu koga se može predvideti ponašanje sistema u funkciji ovih pet faktora. Pokazano je da koncentracija enzima, početni molski odnos supstrata i reakciono vreme imaju najveći uticaj na proces, dok sadržaj vode ne utiče značajno na prinos estra. Pod optimalnim uslovima enzimske sinteze ostvaren je prinos estra oko 92%.
PB  - Serbian Chemical Society, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Lipase catalyzed synthesis of flavor esters in non-aqueous media: Optimization of the yield of pentyl 2-methylpropanoate by statistical analysis
T1  - Sinteza mirisnih estara katalizovana lipazama u nevodenoj sredini - optimizacija prinosa pentil-2-metilpropanoata statističkom analizom
EP  - 1151
IS  - 12
SP  - 1139
VL  - 73
UR  - https://hdl.handle.net/21.15107/rcub_technorep_1304
ER  - 

@article{
author = "Knežević-Jugović, Zorica and Bezbradica, Dejan and Jakovljević, Živana and Dimitrijević-Branković, Suzana and Mijin, Dušan",
year = "2008",
abstract = "In this study, the synthesis of pentyl 2-methylpropanoate employing a commercial lipase from Candida rugosa was investigated, the emphasis being placed on analyzing the effects of various process conditions on the yield of ester. The response surface methodology (RSM) and five-level-five-factor central composite rotatable design (CCRD) were used to evaluate the effects of variables, namely the initial water content, 0.0-2.0% (w/v), the reaction temperature, 35-75°C, the enzyme concentration, 1.0-5.0 g dm-3, the acid/alcohol mole ratio, 1:2-5:2, and the reaction time, 4-48 h, on the yield (%) of ester. The production of pentyl 2-methylpropanoate was optimized and an ester yield response equation was obtained, enabling the prediction of ester yields from known values of the five main factors. It seems that the enzyme concentration, reaction time and acid/alcohol mole ratio predominantly determine the conversion process, while the amount of added water amount had no significant influence on the ester yield. Conversion of around 92 % of the substrate to ester could be realized using a concentration of lipase as low as 4.0 g dm-3 and in a relatively short time (26 h) at 35°C, when a high substrate mole ratio of 2.5 was used., U radu su ispitani uticaji različitih procesnih parametara na sintezu pentil-2-metilpropanoata katalizovanu lipazom iz Candida rugosa. U cilju optimizacije enzimske sinteze estara primenjena je metodologija odzivnih površina u skladu sa odabranim centralnim kompozicionim rotabilnim planom (pet faktora na pet nivoa). Ispitani su uticaji procesnih parametara na prinos estra u sledećim intervalima: početnog sadržaja vode (0,0-2,0 %), temperature (35-75°C), koncentracije enzima (1,0-5,0 g dm-3), početnog molskog udela supstrata (1:2-5:2) i reakcionog vremena (4-48 h). Dobijen je adekvatan matematički model na osnovu koga se može predvideti ponašanje sistema u funkciji ovih pet faktora. Pokazano je da koncentracija enzima, početni molski odnos supstrata i reakciono vreme imaju najveći uticaj na proces, dok sadržaj vode ne utiče značajno na prinos estra. Pod optimalnim uslovima enzimske sinteze ostvaren je prinos estra oko 92%.",
publisher = "Serbian Chemical Society, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Lipase catalyzed synthesis of flavor esters in non-aqueous media: Optimization of the yield of pentyl 2-methylpropanoate by statistical analysis, Sinteza mirisnih estara katalizovana lipazama u nevodenoj sredini - optimizacija prinosa pentil-2-metilpropanoata statističkom analizom",
pages = "1151-1139",
number = "12",
volume = "73",
url = "https://hdl.handle.net/21.15107/rcub_technorep_1304"
}

Knežević-Jugović, Z., Bezbradica, D., Jakovljević, Ž., Dimitrijević-Branković, S.,& Mijin, D.. (2008). Lipase catalyzed synthesis of flavor esters in non-aqueous media: Optimization of the yield of pentyl 2-methylpropanoate by statistical analysis. in Journal of the Serbian Chemical Society
Serbian Chemical Society, Belgrade., 73(12), 1139-1151.
https://hdl.handle.net/21.15107/rcub_technorep_1304

Knežević-Jugović Z, Bezbradica D, Jakovljević Ž, Dimitrijević-Branković S, Mijin D. Lipase catalyzed synthesis of flavor esters in non-aqueous media: Optimization of the yield of pentyl 2-methylpropanoate by statistical analysis. in Journal of the Serbian Chemical Society. 2008;73(12):1139-1151.
https://hdl.handle.net/21.15107/rcub_technorep_1304 .

Knežević-Jugović, Zorica, Bezbradica, Dejan, Jakovljević, Živana, Dimitrijević-Branković, Suzana, Mijin, Dušan, "Lipase catalyzed synthesis of flavor esters in non-aqueous media: Optimization of the yield of pentyl 2-methylpropanoate by statistical analysis" in Journal of the Serbian Chemical Society, 73, no. 12 (2008):1139-1151,
https://hdl.handle.net/21.15107/rcub_technorep_1304 .

TY  - JOUR
AU  - Knežević-Jugović, Zorica
AU  - Damnjanović, Jasmina J.
AU  - Bezbradica, Dejan
AU  - Mijin, Dušan
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1339
AB  - Lipase from Candida rugosa immobilized on Sepabeads EC-EP was shown to catalyze the esterification of geraniol with butyric acid in a predominantly organic system. The immobilization procedure was adjusted to optimize the enzyme activity and the immobilized enzyme was then used for a geranyl butyrate synthesis as a study model. The immobilized enzyme showed favorable performances in an aqueous system and increased the stability in the presence of organic solvents. The response surface methodology and a 5-level-5-factor central composite rotatable design were performed to identify the factors that influence the ester production and to verify whether any changes should be made in their settings to improve this reaction. The initial water content, the reaction temperature, the enzyme concentration, acid/alcohol molar ratio and time of addition of molecular sieves were the variables investigated. The production of the ester was optimized and an ester production response equation was obtained, making it possible to predict ester yields from the known values of the five main factors. The temperature during the esterification reaction was identified as the factor having the greatest impact on the ester yield.
PB  - Association of the Chemical Engineers of Serbia
T2  - Chemical Industry & Chemical Engineering Quarterly
T1  - The immobilization of lipase on Sepabeads: Coupling, characterization and application in geranyl butyrate synthesis in a low aqueous system
EP  - 249
IS  - 4
SP  - 245
VL  - 14
DO  - 10.2298/CICEQ0804245K
ER  - 

@article{
author = "Knežević-Jugović, Zorica and Damnjanović, Jasmina J. and Bezbradica, Dejan and Mijin, Dušan",
year = "2008",
abstract = "Lipase from Candida rugosa immobilized on Sepabeads EC-EP was shown to catalyze the esterification of geraniol with butyric acid in a predominantly organic system. The immobilization procedure was adjusted to optimize the enzyme activity and the immobilized enzyme was then used for a geranyl butyrate synthesis as a study model. The immobilized enzyme showed favorable performances in an aqueous system and increased the stability in the presence of organic solvents. The response surface methodology and a 5-level-5-factor central composite rotatable design were performed to identify the factors that influence the ester production and to verify whether any changes should be made in their settings to improve this reaction. The initial water content, the reaction temperature, the enzyme concentration, acid/alcohol molar ratio and time of addition of molecular sieves were the variables investigated. The production of the ester was optimized and an ester production response equation was obtained, making it possible to predict ester yields from the known values of the five main factors. The temperature during the esterification reaction was identified as the factor having the greatest impact on the ester yield.",
publisher = "Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry & Chemical Engineering Quarterly",
title = "The immobilization of lipase on Sepabeads: Coupling, characterization and application in geranyl butyrate synthesis in a low aqueous system",
pages = "249-245",
number = "4",
volume = "14",
doi = "10.2298/CICEQ0804245K"
}

Knežević-Jugović, Z., Damnjanović, J. J., Bezbradica, D.,& Mijin, D.. (2008). The immobilization of lipase on Sepabeads: Coupling, characterization and application in geranyl butyrate synthesis in a low aqueous system. in Chemical Industry & Chemical Engineering Quarterly
Association of the Chemical Engineers of Serbia., 14(4), 245-249.
https://doi.org/10.2298/CICEQ0804245K

Knežević-Jugović Z, Damnjanović JJ, Bezbradica D, Mijin D. The immobilization of lipase on Sepabeads: Coupling, characterization and application in geranyl butyrate synthesis in a low aqueous system. in Chemical Industry & Chemical Engineering Quarterly. 2008;14(4):245-249.
doi:10.2298/CICEQ0804245K .

Knežević-Jugović, Zorica, Damnjanović, Jasmina J., Bezbradica, Dejan, Mijin, Dušan, "The immobilization of lipase on Sepabeads: Coupling, characterization and application in geranyl butyrate synthesis in a low aqueous system" in Chemical Industry & Chemical Engineering Quarterly, 14, no. 4 (2008):245-249,
https://doi.org/10.2298/CICEQ0804245K . .

TY  - JOUR
AU  - Knežević-Jugović, Zorica
AU  - Šaponjić, Svetlana V.
AU  - Bezbradica, Dejan
AU  - Mijin, Dušan
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1280
AB  - The object of the study was to investigate the process conditions relevant for the pentyl octanoate production with the lipase from Candida rugosa immobilized on Sepabeads EC-EP carrier. This is an epoxide-containing commercial polymethacrylic carrier with suitable characteristics for enzyme immobilization. The immobilized lipase suitable for pentyl octanoate synthesis has been prepared by a direct lipase binding to polymers via their epoxide groups. The enzymatic activity was determined by both hydrolysis of olive oil in an aqueous system and esterification of n-pentanol with octanoic acid in a low aqueous system. The influence of several important reaction parameters such as temperature, initial water content, initial substrate molar ratio, enzyme loading and time of adding of molecular sieves in the system is carefully analyzed by means of an experimental design. Production of the ester was optimized and an ester production response equation was obtained, making it possible to predict ester yields from known values of the five main factors. Almost complete conversion ( gt 99%) of the substrate to ester could be realized, using lipase loading as low as 37 mg/g dry support and in a relatively short time (24 h) at 45ºC, when high initial substrate molar ratio of 2.2 is used.
AB  - U radu su ispitani uticaji procesnih parametara na sintezu pentil-oktanoata pomoću lipaze iz Candida rugosa imobilisane na komercijalni polimetakrilatni nosač (Sepabeads EC-EP). U radu je primenjena metoda imobilizacije enzima koja se zasniva na direktnom vezivanju enzima za nosač preko epoksidne grupe polimera. Aktivnost imobilisanog enzima ispitana je u vodenom sistemu na model reakciji hidrolize maslinovog ulja kao i u nevodenom sistemu na modelu sinteze pentil-oktanoata u izooktanu. Ispitani su uticaji pet procesnih faktora na enzimsku sintezu datog estra primenom metode planiranih eksperimenata i metodologije odzivnih površina i to sadržaja vode, temperature, mase vezanog enzima na nosaču, početnog molarnog odnosa reaktanata i trenutka dodavanja molekulskih sita u sistem. Sinteza estara je optimizovana, izvršena je ocena značajnosti parametara i utvrđen je adekvatan matematički model na osnovu koga se može predvideti ponašanje sistema (prinos estara) u funkciji navedenih faktora.
PB  - Faculty of Technology, Novi Sad
T2  - Acta periodica technologica
T1  - Immobilization of lipase on sepabeads and its application in pentyl octanoate synthesis in a low aqueous system
T1  - Imobilizacija lipaze na komercijalni epoksidni nosač za sintezu pentil-oktanoata u mikrovodenom sistemu
EP  - 152
IS  - 39
SP  - 139
DO  - 10.2298/APT0839139K
ER  - 

@article{
author = "Knežević-Jugović, Zorica and Šaponjić, Svetlana V. and Bezbradica, Dejan and Mijin, Dušan",
year = "2008",
abstract = "The object of the study was to investigate the process conditions relevant for the pentyl octanoate production with the lipase from Candida rugosa immobilized on Sepabeads EC-EP carrier. This is an epoxide-containing commercial polymethacrylic carrier with suitable characteristics for enzyme immobilization. The immobilized lipase suitable for pentyl octanoate synthesis has been prepared by a direct lipase binding to polymers via their epoxide groups. The enzymatic activity was determined by both hydrolysis of olive oil in an aqueous system and esterification of n-pentanol with octanoic acid in a low aqueous system. The influence of several important reaction parameters such as temperature, initial water content, initial substrate molar ratio, enzyme loading and time of adding of molecular sieves in the system is carefully analyzed by means of an experimental design. Production of the ester was optimized and an ester production response equation was obtained, making it possible to predict ester yields from known values of the five main factors. Almost complete conversion ( gt 99%) of the substrate to ester could be realized, using lipase loading as low as 37 mg/g dry support and in a relatively short time (24 h) at 45ºC, when high initial substrate molar ratio of 2.2 is used., U radu su ispitani uticaji procesnih parametara na sintezu pentil-oktanoata pomoću lipaze iz Candida rugosa imobilisane na komercijalni polimetakrilatni nosač (Sepabeads EC-EP). U radu je primenjena metoda imobilizacije enzima koja se zasniva na direktnom vezivanju enzima za nosač preko epoksidne grupe polimera. Aktivnost imobilisanog enzima ispitana je u vodenom sistemu na model reakciji hidrolize maslinovog ulja kao i u nevodenom sistemu na modelu sinteze pentil-oktanoata u izooktanu. Ispitani su uticaji pet procesnih faktora na enzimsku sintezu datog estra primenom metode planiranih eksperimenata i metodologije odzivnih površina i to sadržaja vode, temperature, mase vezanog enzima na nosaču, početnog molarnog odnosa reaktanata i trenutka dodavanja molekulskih sita u sistem. Sinteza estara je optimizovana, izvršena je ocena značajnosti parametara i utvrđen je adekvatan matematički model na osnovu koga se može predvideti ponašanje sistema (prinos estara) u funkciji navedenih faktora.",
publisher = "Faculty of Technology, Novi Sad",
journal = "Acta periodica technologica",
title = "Immobilization of lipase on sepabeads and its application in pentyl octanoate synthesis in a low aqueous system, Imobilizacija lipaze na komercijalni epoksidni nosač za sintezu pentil-oktanoata u mikrovodenom sistemu",
pages = "152-139",
number = "39",
doi = "10.2298/APT0839139K"
}

Knežević-Jugović, Z., Šaponjić, S. V., Bezbradica, D.,& Mijin, D.. (2008). Immobilization of lipase on sepabeads and its application in pentyl octanoate synthesis in a low aqueous system. in Acta periodica technologica
Faculty of Technology, Novi Sad.(39), 139-152.
https://doi.org/10.2298/APT0839139K

Knežević-Jugović Z, Šaponjić SV, Bezbradica D, Mijin D. Immobilization of lipase on sepabeads and its application in pentyl octanoate synthesis in a low aqueous system. in Acta periodica technologica. 2008;(39):139-152.
doi:10.2298/APT0839139K .

Knežević-Jugović, Zorica, Šaponjić, Svetlana V., Bezbradica, Dejan, Mijin, Dušan, "Immobilization of lipase on sepabeads and its application in pentyl octanoate synthesis in a low aqueous system" in Acta periodica technologica, no. 39 (2008):139-152,
https://doi.org/10.2298/APT0839139K . .