N-acetyl-L-arginine ethyl ester synthesis catalysed by bovine trypsin in organic media

The bovine trypsin-catalysed synthesis of N-acetyl-L-arginine ethyl ester f rom N-acetyl-L-arginine and ethanol was studied in various organic solvents (dimethyl sulfoxide, dioxane, dimethylformamide, acetonitrile, acetone, te trahydrofuran, chloroform, toluene, carbon tetrachloride, cyclohexane and n -hexane). The highest yield was achieved in acetonitrile after incubation f or 6 or 24 h. The optimal conditions for ester synthesis in acetonitrile fo r 6 h were as follows: 5.0 mM N-acetyl-L-arginine, 10.0 M ethanol, 7.2 mg t rypsin, 2.87% water, total volume 10.3 mi, pH 7.0 and 30 degrees C. The hyd rolytic activity of trypsin was determined after incubation for 6 days, whe n 87.7% of the original activity remained, suggesting that acetonitrile cau sed little inactivation of the enzyme. The synthetic reaction resulted in a maximal 79.3% conversion under optimized conditions after incubation for 4 8 h. (C) 2000 Elsevier Science B.V. All rights reserved.