Lipase Catalyzed Transesterification of Unsaturated Lipids in a Microemulsion

A series of triglycerides having varying degrees of unsaturation of the acyl groups has been transesterified with stearic acid. It is shown that the position of the double bonds, not the degree of unsaturation, is the decisive factor in the rate of reaction. A A‐6 double bond, which is present in petroselinic acid and ylinolenic acid, prevents reaction. Unsymmetrical triglycerides containing only one acyl group with δ‐6 unsaturation reacts regiospecifically with the A‐6 acyl group facing away from the enzyme. γ‐Linolenic acid can be incorporated into an unhindered triglyceride through lipase catalyzed transesterification, indicating that the active site can in fact accommodate a δ‐6 fatty acid, although not the corresponding triglyceride.