Purification and characterization of hydrolytic haloalkane dehalogenase from Xanthobacter autotrophicus GJ10

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Abstract
A new enzyme, haloalkane dehalogenase, was isolated from the 1,2-dichloroethane-utilizing bacterium X. autotrophicus GJ10. The purified enzyme catalyzed the hydrolytic dehalogenation of n-halogenated C1-C4 alkanes, including chlorinated, brominated and iodinated compounds. The highest activity was found with 1,2-dichloroethane, 1,3-dichloropropane and 1,2-dibromoethane. The enzyme followed Michaelis-Menten kinetics, and the Km for 1,2-dichloroethane was 1.1 mM. Maximum activity was found at pH 8.2 and 37.degree. C. Thiol reagents such as p-chloromercuribenzoate and iodoacetamide rapidly inhibited the enzyme. The protein consists of a single polypeptide chain of a MW of 36,000, and its amino acid composition and N-terminal sequence are given.