Purification and characterization of a bacterial dehalogenase with activity toward halogenated alkanes, alcohols and ethers.
An enzyme that is capable of hydrolytic conversion of halogenated aliphatic hydrocarbons to their corresponding alcohols was purified from a 1,6-dichlorohexane-degrading bacterium. The dehalogenase was found to be a monomeric protein of relative molecular mass 28,000. The affinity for its substrates was relatively low with Km values for short-chain haloalkanes in the range 0.1-0.9 mM. The aliphatic dehalogenase showed a much broader substrate range than has been reported for halidohydrolases so far. Novel classes of substrates include dihalomethanes, C5-C9 1-halo-n-alkanes, secondary alkylhalides, halogenated alcohols and chlorinated ethers. Several of these compounds are important environmental pollutants, e.g. methylbromide, dibromomethane, 1,2-dibromoethane, 1,3-dichloropropene, and bis(2-chloroethyl)ether. The degradation of chiral 2-bromoalkanes appeared to proceed without stereochemical preference. Optically active 2-bromobutane was converted with inversion of configuration at the chiral carbon atom, suggesting that the dehalogenase reaction proceeds by a nucleophilic substitution involving a carboxyl group or base catalysis.
Janssen
D B
DB
Department of Biochemistry, University of Groningen, The Netherlands.
Gerritse
J
J
Brackman
J
J
Kalk
C
C
Jager
D
D
Witholt
B
B
D000192:Actinomycetales / Q000201:enzymology*; D000438:Alcohols / Q000378:metabolism; D000473:Alkanes / Q000378:metabolism; D004987:Ethers / Q000378:metabolism; D006846:Hydrocarbons, Halogenated / Q000378:metabolism*; D006867:Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D013237:Stereoisomerism; D013379:Substrate Specificity
D000438:Alcohols; D000473:Alkanes; D004987:Ethers; D006846:Hydrocarbons, Halogenated; D006867:Hydrolases; C046137:haloalkane dehalogenase