Determination of the carbon kinetic isotope effects on propane hydroxylation mediated by the methane monooxygenases from Methylococcus capsulatus (Bath) by using stable carbon isotopic analysis.
Authentic propane with known position-specific carbon isotope composition at each carbon atom was subjected to hydroxylation by the particulate and soluble methane monooxygenase (pMMO and sMMO) from Methylococcus capsulatus (Bath), and the corresponding position-specific carbon isotope content was redetermined for the product 2-propanol. Neither the reaction mediated by pMMO nor that with sMMO showed an intermolecular (12)C/(13)C kinetic isotope effect effect on the propane hydroxylation at the secondary carbon; this indicates that there is little structural change at the carbon center attacked during formation of the transition state in the rate-determining step. This finding is in line with the concerted mechanism proposed for pMMO (Bath), and suggested for sMMO (Bath), namely, direct side-on insertion of an active "O" species across the C-H bond, as has been previously reported for singlet carbene insertion.
Huang
Ded-Shih
DS
Department of Chemistry, National Cheng-Kung University, Tainan 701 (Taiwan).
Wu
Suh-Huey
SH
Wang
Yane-Shih
YS
Yu
Steve S-F
SS
Chan
Sunney I
SI
D019840:2-Propanol / Q000032:analysis / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D002247:Carbon Isotopes; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006865:Hydrogenation; D006900:Hydroxylation; D007700:Kinetics; D020619:Methylococcus capsulatus / Q000201:enzymology*; D010105:Oxygenases / Q000737:chemistry* / Q000378:metabolism; D011407:Propane / Q000737:chemistry*
D000475:Alkenes; D002247:Carbon Isotopes; C013658:propylene; D010105:Oxygenases; C021555:methane monooxygenase; D019840:2-Propanol; D011407:Propane