tailieunhanh - Báo cáo khoa học: Adventitious reactions of alkene monooxygenase reveal common reaction pathways and component interactions among bacterial hydrocarbon oxygenases

Alkene monooxygenase (AMO) fromRhodococcus rhodochrous(formerly Nocardia corallina) B-276 belongs to a family of multicomponent nonheme binuclear iron-centre oxygenases that includes the soluble methane mono-oxygenases (sMMOs) found in some methane-oxidizing bacteria. The enzymes catalyse the insertion of oxygen into organic substrates (mostly hydrocarbons) at the expense of O2and NAD(P)H. | ềFEBS Journal Adventitious reactions of alkene monooxygenase reveal common reaction pathways and component interactions among bacterial hydrocarbon oxygenases William L. J. Fosdike1 Thomas J. Smith1 2 and Howard Dalton1 1 Department of BiologicalSciences University of Warwick Coventry UK 2 BiomedicalResearch Centre Sheffield Hallam University UK Keywords alkene monooxygenase alkyne component interactions peroxide shunt reaction turnover-dependent inhibition Correspondence H. Dalton Department of Biological Sciences University of Warwick Coventry CV4 7AL UK Fax 44 24 76523568 Tel 44 24 76523552 E-mail Website http res id 4 http schools sci biomed bmrc Received 24 January 2005 revised 14 March 2005 accepted 21 March 2005 doi Alkene monooxygenase AMO from Rhodococcus rhodochrous formerly Nocardia corallina B-276 belongs to a family of multicomponent nonheme binuclear iron-centre oxygenases that includes the soluble methane monooxygenases sMMOs found in some methane-oxidizing bacteria. The enzymes catalyse the insertion of oxygen into organic substrates mostly hydrocarbons at the expense of O2 and NAD P H. AMO is remarkable in its ability to oxidize low molecular-mass alkenes to their corresponding epoxides with high enantiomeric excess. sMMO and other well-characterized homologues of AMO exhibit two adventitious activities 1 turnoverdependent inhibition by alkynes and 2 activation by hydrogen peroxide in lieu of oxygen and NAD P H the peroxide shunt reaction . Previous studies of the AMO had failed to detect these activities and opened the possibility that the mechanism of AMO might be fundamentally different from that of its homologues. Thanks to improvements in the protocols for cultivation of R. rhodochrous B-276 and purification and assay of AMO it has been possible to detect and characterize turnover-dependent inhibition of AMO by propyne and ethyne