Association with natural polymers modifies lipase selectivity

Abstract

It was shown in the previous communication that the specificity of lipases can be altered through physico‐chemical modifications with defined polymers. The same effect is achieved when lipases form associations with natural polymers. In this communication, non‐covalent modifications of lipases with other polymers, such as carbohydrates and proteins, were investigated and again a correlation between the polarity of the polymer and that of the liberated fatty acids was established. This was most clearly seen following hydrolysis of the pectin in a pectin‐lipase associate: The ratio of liberated oleic‐ to stearic acid changed from 2.2:1 to 1:1 when pectin hydrolysis was stopped. The natural oleic versus stearic ratio of the pure lipase was 0.5:1. Use of a model system consisting of triglycerides containing only one fatty acid provided an explanation for modified lipase specificity. It is suggested that the potential penetration depth of the lipase complex does not determine the profile of liberated fatty acids, but rather that the determining factor is the stabilisation of the modified lipase‐oil/water interface‐complex and the different energy levels in the transition state during lipolysis. A partial purification of a commercial lipase preparation from Mucor javanicus was also performed.