ENZYMATIC PEPTIDE-SYNTHESIS IN FROZEN AQUEOUS SYSTEMS - INFLUENCE OF MODIFIED REACTION CONDITIONS ON THE PEPTIDE YIELD

The alpha-chymotrypsin (EC 3.4.21.1)-catalyzed reaction of Mal-Phe-OMe with H-Leu-NH2 has been studied under a range of reaction conditions, for example various cryogenic reagents for shock-freezing, addition o f dimethyl sulfoxide (DMSO) and decreased reaction temperatures down t o 213 K, It has been shown that the peptide yield is independent of th e method of shock-freezing. The optimal reaction temperature was betwe en 263 K and 248 K, Lower temperatures result in clearly retarded reac tions. Addition of DMSO leads to decreasing peptide yields. It is cert ain that the peptide bond formation is catalyzed by the active enzyme, since unspecific protein surface catalysis gave no peptide yields at all.