Complementary and synergistic roles in enzyme-catalyzed regioselective and complete hydrolytic deprotection of O-acetylated β-D-glucopyranosides of N-arylacetohydroxamic acids.

An efficient chemoenzymatic synthesis of β-d-glucopyranosides of N-arylacetohydroxamic acids 3a–c was achieved by the chemoselective O-deacetylation of 1a–c under mild, neutral conditions, with no accompanying N-deacetylation. Lipase AS Amano from Aspergillus niger (LAS) and carboxylesterase from Streptomyces rochei (CSR) played complementary, synergistic roles in the O-deacetylation of 1a and its partially O-deacetylated intermediates. An intramolecular O-acetyl migration, which proceeded simultaneously, also accelerated the overall reaction rate. Under weakly acidic conditions at pH 5.0, where the intramolecular O-acetyl migration is markedly slower, LAS, CSR, and porcine liver esterase (PLE) exhibited different regioselective O-deacetylation activities. LAS and PLE showed regioselective 3-O-deacetylation and 2-O-deacetylation activity, respectively, for 1a and its tri-O-acetyl derivatives (4-7). CSR showed marked preferences for 3-O-deacetylation of 2,3,6-tri-O-acetyl intermediate 5 and 4-O-deacetylati...