CHARACTERIZATION OF A NOVEL ENANTIOSELECTIVE HALOHYDRIN HYDROGEN-HALIDE-LYASE

Enzymes I(a) and I(b) of Corynebacterium sp. strain N-1074 exhibit halohydrin hydrogen-halide-lyase (H-lyase) activity, catalyzing the interconversion of halohydrins to epoxides and hydrogen halide. H-lyase B produced in a recombinant Escherichia coli strain carrying one of the enzyme genes of Corynebacterium sp. strain N-1074 was purified and characterized. The purified enzyme catalyzed the transformation of prochiral 1,3-dichloro-2-propanol (DCP) into R-rich epichlorohydrin (ECH). The apparent K(m) values for DCP, ECH, and chloride were calculated to be 1.03, 5.00, and 4.00 mM, respectively. Maximum activity for the conversion of DCP to ECH was found at pH 8.0 to 9.0, and that for the reverse reaction was found at about pH 5.0. H-lyase B seemed to be identical to enzyme I(b) of Corynebacterium sp. strain N-1074 from the comparison of the properties of each. The properties of H-lyase B and H-lyase A, which had been previously purified from another recombinant carrying its gene from Corynebacterium sp. strain N-1074, were also compared.