Chemical modification of alpha-chymotrypsin for obtaining high transesterification activity in low water organic media

Abstract

Alpha-chymotrypsin was made more hydrophilic by modifying 11 (out of 16) ε-amino groups with pyromellitic dianhydride. The hydrophilic preparation was precipitated with n-propanol. This preparation gave significantly higher initial rates at the optimum a_w (127.51 nmol mg⁻¹ min⁻¹ in n-octane and 21.30 nmol mg⁻¹ min⁻¹ in acetonitrile at a_w=0.33) compared with the lyophilized preparation (53.50 nmol mg⁻¹ min⁻¹ in n-octane and 0.26 nmol mg⁻¹ min⁻¹ in acetonitrile at a_w=0.97). FT-IR showed that the precipitate of modified alpha-chymotrypsin has a higher content of alpha-helices and beta-sheets compared to the lyophilized powder.

• Alpha-chymotrypsin
• chemical modification
• low water organic media
• pyromellitic dianhydride
• transesterification reactions