The Candida rugosa lipase catalyzed synthesis of amyl isobutyrate in organic solvent and solvent-free system: A kinetic study

Abstract

The Candida rugosa lipase catalyzed esterification of butyric acid with amyl alcohol in isooctane and in solvent-free system was studied. Nearly complete conversion ( gt 95%) of substrates was achieved using low enzyme amount of 0.5% (w/v) at 45 degrees C. The initial rates of esterification were attempted to correlate with concentrations of substrates by various bisubstrate kinetic models. The reaction rate of esterification in isooctane could be described with a ping-pong bi-bi mechanism and inhibition by amyl alcohol. Obtained specificity constants indicate that lipase from C. rugosa has higher affinity towards acid substrate. The rate of esterification in solvent-free system could not be described with applied bisubstrate models probably due to denaturation of lipase in absence of solvent at high concentrations of both substrates. Nevertheless, the maximum initial rate in solvent-free system was higher than corresponding values in isooctane which indicates that solvent-free system has good perspectives for industrial utilization at lower S/E ratios.