Biodehalogenation. Epoxidation of halohydrins, epoxide opening, and transhalogenation by a Flavobacterium species

Abstract

Cell-free extracts of a Flavobacterium sp.efficiently convert 2,3-dibromopropanol into glycerol via the sequence: dibromopropanol -epibromohydrin -> dihydroxybromopropane -* glycidol -glycerin. The c X^Varbon-halogen bonds are present in a wide array of biocides and anesthetics. Moreover, -halo acids are widely employed as enzymatic inhibitors (Webb, 1966;Leasure, 1964). Indeed, because of the toxicity of organic halides and their inhibitory capacities it is understandable that the full scope of enzymatic dehalogenation remains to be portrayed. Nevertheless some remarkable transformations have been recorded. Thus, carbon tetrachloride is reduced to chloroform by dogs (Butler, 1961) and converted into carbon dioxide by monkeys (McCollister et al., 1951) and rat liver homogenates (Rubinstein and Kanics, 1964). The insecticide

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

“…3) Similar enzyme activities have been found in Flavobacterium, 29) Pseudomonas, 26) and Arthrobacter. 26 ) Recently, Janssen and co-workers have purified and characterized an enzyme from Arthrobacter sp.…”

Degradation of Epichlorohydrin and Halohydrins by Bacterial Cultures Isolated from Freshwater Sediment

“…Although growth on vicinal halohydrins has been found previously (Castro & Bartnicki, 1968;Stucki & Leisinger, 1983;Janssen et al, 1985), growth on epichlorohydrin had not been reported (Krijgsheld & van der Gen, 1986).…”

“…There are indications that bromoethanol, epichlorohydrin and chloroethylethers may be hydrolytically dehalogenated by bacterial dehalogenases (Janssen et al, 1988 ; D. B. Janssen, A. J. van den Wijngaard & J. Prins, unpublished), although it is not clear whether the activities are involved in the utilization of these compounds. Enzymic formation of epoxides from halohydrins has been found in an organism that utilizes 2,3-dibromo-l-propanol (Castro & Bartnicki, 1968 ;Bartnicki & Castro, 1969).…”

Halohydrin Dehalogenases Are Structurally and Mechanistically Related to Short-Chain Dehydrogenases/Reductases

“…Hydrolytic dehalogenases have been studied extensively, which has resulted in detailed insight into the structure and mechanism of several enzymes of this class (8,33). For other dehalogenases, structural and mechanistic data are hardly available.Halohydrin dehalogenases, also referred to as haloalcohol dehalogenases or halohydrin hydrogen-halide lyases, occur in the degradation pathways of halopropanols and 1,2-dibromoethane, where they catalyze the nucleophilic displacement of a halogen by a vicinal hydroxyl group in halohydrins, yielding an epoxide, a proton, and a halide ion (7,22,30,31). These enzymes also efficiently catalyze the reverse reaction, the halogenation of epoxides, and the dehalogenation of vicinal chlorocarbonyls to hydroxycarbonyls (2, 14, 31).…”