Enzymatic peptide synthesis in organic solvent with different zeolites as immobilization matrixes

A series of zeolite immobilized alpha-chymotrypsin and thermolysin with microporous Y zeolites (HY, NH4Y, NaY) and mesoporous dealuminized DAY zeolites (HDAY, HNH(4)DAY) as matrixes have been prepared to catalyze peptide bond formation in organic solvents for the first time. The results indicated that most zeolite immobilized enzymes were active for peptide syntheses in organic media, and still had catalytic activity to some extent after being reused five times. According to the results, the immobilization effect of microporous Y zeolite was better than that of mesoporous DAY zeolite, suggesting that microporous Y zeolite can form more powerful hydrogen bonds with enzyme molecules since there are more hydroxyl groups on the Y zeolite than on the DAY zeolite. In addition, the influences of some reaction conditions such as reaction time and water content of the solvent on the enzymatic peptide synthesis were also studied and optimized. For the two kinds of proteases, NH4Y zeolite did not show its advantages for thermolysin, but was more suitable for or-chymotrypsin as an immobilization matrix. (C) 2000 Elsevier Science Ltd. All rights reserved.