title: Assessing the substrate selectivities and enantioselectivities of eight novel Baeyer-Villiger monooxygenases toward alkyl-substituted cyclohexanones.
abstract: Genes encoding eight Baeyer-Villiger monooxygenases have recently been cloned from bacteria inhabiting a wastewater treatment plant. We have carried out a systematic investigation in which each newly cloned enzyme, as well as the cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871, was used to oxidize 15 different alkyl-substituted cyclohexanones. The panel of substrates included equal numbers of 2-, 3-, and 4-alkyl-substituted compounds to probe each enzyme's stereoselectivity toward a homologous series of synthetically important compounds. For all 4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in >/=98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer-Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds. More commonly, however, they showed only one type of selectivity. Nonetheless, enzymes with such properties might be useful as parts of a two-step bioprocess where an initial kinetic resolution is followed by a regioselective oxidation on the isolated, optically pure ketone.
authors.affiliation: 127 Chemistry Research Building, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Kyte
authors.forename: Pierre
authors.initials: P
authors.lastname: Rouvière
authors.forename: Qiong
authors.initials: Q
authors.lastname: Cheng
authors.forename: Jon D
authors.initials: JD
authors.lastname: Stewart
mesh_terms: D003512:Cyclohexanones / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D003512:Cyclohexanones; D006899:Mixed Function Oxygenases