Characterization of the epoxide hydrolase from an epichlorohydrin‐degrading Pseudomonas sp.

Abstract

An epoxide hydrolase was purified to homogeneity from the epichlorohydrin-utilizing bacterium Pseudomonas sp. strain AD1. The enzyme was found to be a monomeric protein with a molecular mass of 35 kDa. With epichlorohydrin as the substrate, the enzyme followed Michaelis-Menten kinetics with a K , value of 0.3 mM and a Vmax of 34 pmol . min-' . mg protein-'. The epoxide hydrolase catalyzed the hydrolysis of several epoxides, including epichlorohydrin, epibromohydrin, epoxyoctane and styrene epoxide. With all chiral compounds tested, both stereoisomers were converted. Amino acid sequencing of cyanogen bromide-generated peptides did not yield sequences with similarities to other known proteins.

The X-ray Structure of Epoxide Hydrolase from Agrobacterium radiobacter AD1

“…However, much progress has recently also been made in the characterization of bacterial epoxide hydrolases (5,6,7). These enzymes show a significant sequence homology with those of mammalian origin.…”

“…They can be easily obtained in large amounts, and they exhibit enantioselectivity with various industrially important epoxides, which makes them promising biocatalysts for the large scale preparation of enantiopure epoxides and/or their corresponding vicinal diols (8). In particular, extensive studies have been performed on the epoxide hydrolase from Agrobacterium radiobacter AD1, a Gram-negative bacterium that is able to use the environmental pollutant epichlorohydrin as its sole carbon and energy source (5,6,8). This epoxide hydrolase is a soluble monomeric globular protein of 35 kDa with a broad substrate range.…”

Cloning of Two Halohydrin Hydrogen–Halide–Lyase Genes ofCorynebacteriumsp. Strain N-1074 and Structural Comparison of the Genes and Gene Products

“…Recently, Jacobs et al 27) purified the opoxide hydrolase from Pseudomonas sp., and found the amino acid sequence of the amino termini of the intact protein and cyanogen bromide-generated peptides. They did not find that their sequences had similarity with any of the sequences in the SWISS-PROT Protein Database A contiguous open reading frame was not found in the case of the hheB gene.…”

“…strain N-I074, although Jacobs et al mentioned that the other peptide (fragment 2 in ref. 27) was probably the carboxyl terminus of Pseudomonas sp. epoxide hydrolase.…”

“…2B) had high homology (56% identical amino acid residues) with one of the peptides (fragment 1 in ref. 27) from Pseudomonas sp. epoxide hydrolase.…”