title: Toluene monooxygenase-catalyzed epoxidation of alkenes.
abstract: Several toluene monooxygenase-producing organisms were tested for their ability to oxidize linear alkenes and chloroalkenes three to eight carbons long. Each of the wild-type organisms degraded all of the alkenes that were tested. Epoxides were produced during the oxidation of butene, butadiene, and pentene but not hexene or octadiene. A strain of Escherichia coli expressing the cloned toluene-4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 was able to oxidize butene, butadiene, pentene, and hexene but not octadiene, producing epoxides from all of the substrates that were oxidized. A T4MO-deficient variant of P. mendocina KR1 oxidized alkenes that were five to eight carbons long, but no epoxides were detected, suggesting the presence of multiple alkene-degrading enzymes in this organism. The alkene oxidation rates varied widely (ranging from 0. 01 to 0.33 micromol of substrate/min/mg of cell protein) and were specific for each organism-substrate pair. The enantiomeric purity of the epoxide products also varied widely, ranging from 54 to >90% of a single epoxide enantiomer. In the absence of more preferred substrates, such as toluene or alkenes, the epoxides underwent further toluene monooxygenase-catalyzed transformations, forming products that were not identified.
authors.affiliation: Envirogen, Inc., Lawrenceville, New Jersey 08648, USA.
authors.forename: K
authors.initials: K
authors.lastname: McClay
authors.forename: B G
authors.initials: BG
authors.lastname: Fox
authors.forename: R J
authors.initials: RJ
authors.lastname: Steffan
mesh_terms: D000475:Alkenes / Q000378:metabolism*; D003001:Cloning, Molecular; D004852:Epoxy Compounds / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000475:Alkenes; D004852:Epoxy Compounds; D007527:Isoenzymes; D011994:Recombinant Proteins; D010105:Oxygenases; C068610:toluene-4-monooxygenase