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 aw (127.51 nmol mg−1 min−1 in n-octane and 21.30 nmol mg−1 min−1 in acetonitrile at aw=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 aw=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.