A novel dihydrocoumarin hydrolase from Acinetobacter calcoaceticus: application to the production of useful compounds

A novel aromatic lactone hydrolyzing enzyme, dihydrocoumarin (DHC) hydrolase, was isolated from Acinetobacter calcoaceticus F46. Primary structure of the enzyme showed high similarity to those of the esterases of Pseudomonas strains and bacterial non-heme haloperoxidases. The enzyme catalyzed both hydrolysis of ester compounds such as aromatic lactones and bromination of monochlorodimedon. DHC hydrolase also could hydrolyze methyl esters of β-acetylthioisobutyrate and cetraxate. The products of these reactions were identified as d-β-acetylthioisobutyrate (>99% ee) and cetraxate, respectively, suggesting that the hydrolysis reactions catalyzed by DHC hydrolase are enantio- and/or regio-selective. The reaction products, cetraxate and d-β-acetylthioisobutyrate, are useful compounds as pharmaceuticals.