van Hylckama Vlieg J E, Kingma J, van den Wijngaard A J, Janssen D B
Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
Appl Environ Microbiol. 1998 Aug;64(8):2800-5. doi: 10.1128/AEM.64.8.2800-2805.1998.
Rhodococcus sp. strain AD45 was isolated from an enrichment culture on isoprene (2-methyl-1,3-butadiene). Isoprene-grown cells of strain AD45 oxidized isoprene to 3,4-epoxy-3-methyl-1-butene, cis-1, 2-dichloroethene to cis-1,2-dichloroepoxyethane, and trans-1, 2-dichloroethene to trans-1,2-dichloroepoxyethane. Isoprene-grown cells also degraded cis-1,2-dichloroepoxyethane and trans-1, 2-dichloroepoxyethane. All organic chlorine was liberated as chloride during degradation of cis-1,2-dichloroepoxyethane. A glutathione (GSH)-dependent activity towards 3, 4-epoxy-3-methyl-1-butene, epoxypropane, cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroepoxyethane was detected in cell extracts of cultures grown on isoprene and 3,4-epoxy-3-methyl-1-butene. The epoxide-degrading activity of strain AD45 was irreversibly lost upon incubation of cells with 1,2-epoxyhexane. A conjugate of GSH and 1, 2-epoxyhexane was detected in cell extracts of cells exposed to 1, 2-epoxyhexane, indicating that GSH is the physiological cofactor of the epoxide-transforming activity. The results indicate that a GSH S-transferase is involved in the metabolism of isoprene and that the enzyme can detoxify reactive epoxides produced by monooxygenation of chlorinated ethenes.
红球菌属菌株AD45是从以异戊二烯（2-甲基-1,3-丁二烯）为基质的富集培养物中分离得到的。在以异戊二烯生长的AD45菌株细胞中，异戊二烯被氧化为3,4-环氧-3-甲基-1-丁烯，顺式-1,2-二氯乙烯被氧化为顺式-1,2-二氯环氧乙烷，反式-1,2-二氯乙烯被氧化为反式-1,2-二氯环氧乙烷。以异戊二烯生长的细胞也能降解顺式-1,2-二氯环氧乙烷和反式-1,2-二氯环氧乙烷。在顺式-1,2-二氯环氧乙烷降解过程中，所有有机氯都以氯离子形式释放出来。在以异戊二烯和3,4-环氧-3-甲基-1-丁烯生长的培养物的细胞提取物中，检测到了一种依赖谷胱甘肽（GSH）的针对3,4-环氧-3-甲基-1-丁烯、环氧丙烷、顺式-1,2-二氯环氧乙烷和反式-1,2-二氯环氧乙烷的活性。将细胞与1,2-环氧己烷一起孵育后，AD45菌株的环氧化物降解活性不可逆地丧失。在暴露于1,2-环氧己烷的细胞的提取物中检测到了GSH与1,2-环氧己烷的结合物，这表明GSH是环氧化物转化活性的生理辅因子。结果表明，一种谷胱甘肽S-转移酶参与了异戊二烯的代谢，并且该酶可以使由氯化乙烯单加氧产生的活性环氧化物解毒。
