Study on the enzyme's 1,3-positional specificity during lipozyme TL-mediated biodiesel production

Abstract

The 1,3-positional specificity of lipases plays an important role in obtaining high yield of products especially in the methanolysis for biodiesel production. In this paper, the effect of solvent and water activity on the enzyme's 1,3-positional specificity during lipozyme TL-catalyzed methanolysis of triglyceride (TAG) for biodiesel production was explored. Then the effect of organic solvent and water activity on the methanolysis of monoglyceride (MAG) was further carried out from the aspect of a kinetics study. It was found that either in the methanolysis of TAG or MAG, the 1,3-positional specificity of lipozyme TL correlated well with the log P of organic solvents. With the increase of the log P of the organic solvent, the enzyme's 1,3-positional specificity decreased. Interestingly, in each group of solvents (ketones, alkanes and chlorinated hydrocarbon), the 1,3-positional specificity of the lipase improved with water activity increasing from 0.11 to 0.53, while it decreased with water activity further increasing from 0.53 to 0.97. Further exploration on the related mechanism with a molecular dynamics simulation revealed that the organic solvent influenced the dehydration state of the lipase, which might subsequently influence the lipase's 1,3-positional specificity.