A unique deuterium/proton exchange during cytochrome P-450 mediated expoxidation of propene and butene.
A cytochrome P-450 LM2 reconstituted system mediated expoxidations of small terminal alkenes to the corresponding alkyloxiranes. This oxidation was accompanied by a stereoselective proton exchange of the E proton. Propene was oxidized in D2O to trans-3-deuterio-2-methyloxirane, and E-1-deuteriopropene was epoxidized in H2O to methyloxirane. Thus, oxidation occurred with complete exchange. The epoxidation of 1-butene in D2O generated a mixture of 86% ethyloxirane and 14% E-3-deuterio-2-ethyloxirane. Reaction of E-1-deuterio-1-butene produced 10-30% ethyloxirane and 70-90% trans-3-deuterio-2-ethyloxirane. Larger terminal alkenes in the homologous series did not undergo such an exchange. A mechanism involving formation of organoiron porphyrin intermediates is proposed. Stereoselective deprotonation by a basic amino acid residue producing an iron carbene complex is proposed as the mechanism of exchange with water.
Groves
J T
JT
Department of Chemistry, Princeton University, New Jersey 08544.
Fish
K M
KM
Avaria-Neisser
G E
GE
Imachi
M
M
Kuczkowski
R L
RL
D000475:Alkenes / Q000378:metabolism*; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism*; D004988:Ethers, Cyclic / Q000378:metabolism*; D007700:Kinetics; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction
D000475:Alkenes; D004852:Epoxy Compounds; D004988:Ethers, Cyclic; D003577:Cytochrome P-450 Enzyme System; C013658:propylene; C021639:2-butene