Dehalogenase specificity

Bisaillon, A. B., Lepine, R, Deziel, E., VUlemur, R. Identification and characterization of a novel CprA reductive dehalogenase specific to highly chlorinated phenols from Desulfitobacterium hajhiense ima.PCP-. Appl Environ Microbiol 2010, 76,7536-7540. 

Specific Activity (pmol Bromide Produced per mg Protein per min) of Dehalogenase from Selected Species of Mycobacteria toward 1,2-dibromoethane... 

Neumann A, A Siebert, T Trescher, S Reinhardt, G Wohlfarth, G Dickert (2002) Tetrachloroethene reductive dehalogenase of Dehalospirillum multivorans substrate specificity of the native enzyme and its cor-ronoid cofactor. Arch Microbiol 111 420-426. 

A spore-forming strain of Desulfitobacterium chlororespirans was able to couple the dechlorination of 3-chloro-4-hydroxybenzoate to the oxidation of lactate to acetate, pyruvate, or formate (Sanford et al. 1996). Whereas 2,4,6-trichlorophenol and 2,4,6-tribro-mophenol supported growth with the production of 4-chlorophenol and 4-bromophenol, neither 2-bromophenol nor 2-iodophenol was able to do so. The membrane-bound dehalogenase contains cobalamin, iron, and acid-labile sulfur, and is apparently specific for ortho-substituted phenols (Krasotkina et al. 2001). 

Bacterial strains were isolated that could grow on R-CPA [(R)-2-chloropropanoic acid], but not on S-CPA, because although both isomers were dehalogenated by different R and S specific dehalogenase isozymes, the -lactic acid formed from the S-CPA could not be metabolised. 

Whole cells are used in stirred tanks with pH control, producing fS )-2-chloropropanoic acid in 50% yield from the racemate (0.3 M) with an enantiomeric excess of over 95%. This approach was selected in preference to other methods of resolution such as acylation of the racemate and then stereoselective hydrolysis. The dehalogenase enzyme is specific for substrates with a carboxyl group and a 2-chloro or bromo substituent. No cofactor or metal ion is required and reaction involves an inversion of configuration. 

Damborsky, J., Rome, E., Jesenska, A., Nagata, Y., Klopman, G., Peijnenburg, W.J.G.M. (2001) Structure-specificity relationships for haloalkane, dehalogenases. Environ. Toxicol. Chem. 20, 2681-2689. 

S)-2-chloropropionic acid by enantioselective dehalogenation racemate (R)-specific dehalogenase... 

Neumann A, Seibeet A, Teesghee T, Reinhaedt S, WoHLEAETH G and Diekeet G (2002) Tetro-chloroethene reductive dehalogenase of Dehalospiril-lum multivorans substrate specificity of the native enzyme and its corrinoid cofactor. Arch Microbiol 177 420-426. 

Two mitochondrial isoforms of rat A A -enoyl-CoA isomerase have been described, the first one being a mitochondrial short-chain isomerase with a preferred chain-length specificity of Cg-C. This heat-stable enzyme has a subunit size of 30kDa and a pi value of about 9.5. The second isoform found in rat liver is also mitochondrial, but its catalytic rate is greatest for Cjo-Cn enoyl-CoA substrates and it is not clofibrate-inducible, unlike the rat liver short-ehain specific enzyme. The cDNA sequence of the mitochondrial short-chain isomerase has been published and its amino acid sequence shows similarity to the mitochondrial 2-enoyl-CoA hydratase 1. Currently the hydratase/isomerase family has about 30 known eukaryotic and prokaryotic members and the structure for two members has been published (rat mitochondrial 2-enoyl-CoA hydratase 1 and Pseudomonas sp. 4-chlorobenzoyl-CoA dehalogenase ). They all possess a conserved fingerprint of Val-Ser-X-Ile-Asn-Qy-X-X-X-Ala-Gly-Qy-X-Leu-X-X-X-X-Cys-Asp-Tyr, potentially have similar main chain folding, and catalyze reactions with carboxylic CoA esters as substrates. "... 

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