Sol-gel immobilization of serine proteases for application in organic solvents

The serine proteases α‐chymotrypsin, trypsin, and subtilisin Carlsberg were immobilized in a sol‐gel matrix and the effects on the enzyme activity in organic media are evaluated. The percentage of immobilized enzyme is 90% in the case of α‐chymotrypsin and the resulting specific enzyme activity in the transesterification of N‐acetyl‐L‐phenylalanine ethyl ester with 1‐propanol in cyclohexane is 43 times higher than that of a nonimmobilized lyophilized α‐chymotrypsin. The activities of trypsin and subtilisin Carlsberg are enhanced with 437 and 31 times, respectively. The effect of immobilization on the enzyme activity is highest in hydrophobic solvents. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 154–158, 2001.