Pig Liver Esterase Catalyzed Hydrolysis of Methyl 2,3-Di-O-Acetyl-5-Deoxy-α- and β-D-Arabinofuranosides

Abstract

The regioselectivity of a pig liver esterase (PLE) catalyzed hydrolysis of methyl 2,3-di-O-acetyl-5-deoxy-α-D-arabinofuranoside (1) and methyl 2,3-di-O-acetyl-5-deoxy-β-D-arabinofuranoside (2) was established by GLC. Diacetate 1 gave exclusively methyl 3-O-acetyl-5-deoxy-α-D-arabinofuranoside while diacetate 2 produced both methyl 2-O-acetyl-5-deoxy-β-D-arabinofuranoside and methyl 3-O-acetyl-5-deoxy-β-D-arabinofuranoside which were resistant to subsequent hydrolysis. The Michaelis constants and maximal velocities were determined for 1 and 2. The first-order rate constants were computed for 1, 2, and all corresponding monoacetates. The results were evaluated on the basis of a Jones's active-site model for PLE and the additional criteria valid for acetyl esters of pentofuranosides were proposed.