THERMOLYSIN-CATALYZED PEPTIDE-SYNTHESIS IN AQUEOUS POLYMER 2-PHASE SYSTEMS

A proteolytic enzyme, thermolysin, was covalently immobilized to dextr an which has a small number of carboxyl groups. Enzymatic synthesis of aspartame derivative (Boc-Asp-Phe-OMe) using the dextran-conjugated t hermolysin was carried out in an aqueous polymer two-phase system, whe re poly(ethylene glycol) (PEG) and dextran dissolved in water make a p hase separation. The yield of the peptide catalyzed by the dextran-con jugated thermolysin was higher than that using a native enzyme in the aqueous polymer two-phase system partly due to the effect of the micro environment around the modified enzyme and partly due to the ''mass-la w'' effect (the preferential dissolution of the peptide product into t he PEG phase). The aqueous polymer two-phase system would be very usef ul to carry out enzymatic organic syntheses in high yields.