Control of the regiospecificity of Candida antarctica lipase by polarity.

Candida antarctica lipase has generally been known to be nonregiospecific. This report, however, showed that its regiospecificity was linearly correlated to the index of polarity of the reaction mixture, which was calculated based on the dielectric constant of the components. Thus, it was strongly indicated that the regiospecificity depended on the polarity of the environment; the higher the polarity, the stricter the regiospecificity. The highest 1(3)-regiospecificity was obtained in the transesterification of oil with ethanol among other alcohols investigated. Although methanol, which is more polar than ethanol, was expected to give highest regiospecificity, it was fatal to the lipase. The transesterification of oil with ethanol (1:10, wt/wt) at 30 degrees C for three hours efficiently accumulated 2-monoacylglycerols without significant fatty acid (FA) specificity. Thus, it was successfully applied to regiospecifically analyze FA composition of triacylglycerols containing saturated and unsaturated FAs of C4-C24.