Janssen D B, Gerritse J, Brackman J, Kalk C, Jager D, Witholt B
Department of Biochemistry, University of Groningen, The Netherlands.
Eur J Biochem. 1988 Jan 15;171(1-2):67-72. doi: 10.1111/j.1432-1033.1988.tb13759.x.
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.
从一株能降解1,6 - 二氯己烷的细菌中纯化出一种可将卤代脂肪烃水解转化为相应醇类的酶。该脱卤酶是一种相对分子质量为28,000的单体蛋白。它对底物的亲和力相对较低，短链卤代烷的Km值在0.1 - 0.9 mM范围内。脂肪族脱卤酶的底物范围比迄今报道的卤代水解酶要广泛得多。新型底物包括二卤甲烷、C5 - C9 1 - 卤代正烷烃、仲烷基卤、卤代醇和氯代醚。其中几种化合物是重要的环境污染物，例如甲基溴、二溴甲烷、1,2 - 二溴乙烷、1,3 - 二氯丙烯和双(2 - 氯乙基)醚。手性2 - 溴代烷烃的降解似乎没有立体化学偏好。光学活性的2 - 溴丁烷在手性碳原子处构型翻转的情况下被转化，这表明脱卤酶反应是通过涉及羧基的亲核取代或碱催化进行的。
