We have examined the 5-exo-hydroxylation of camphor by cytochrome P450 in [18O] water/buffer solution. In the NADH O2-dependent reaction of the reconstituted multienzyme system, no 18O-label is observed in the product alcohol. Similarly, in the m-chloroperbenzoic acid or cumene hydroperoxide supported reactions with ferric P450, solvent oxygen is not incorporated into hydroxycamphor. When the analagous reaction is carried out using iodosobenzene as the exogenous oxidant, however, the alcoholic oxygen of the product is derived entirely from the solvent. These results cannot be explained by equilibration of the iodosobenzene oxygen with solvent water before reacting with P450, and suggest a unique mechanism for iodosobenzene-supported P450 oxygenations. We propose two distinct mechanistic activities for cytochrome P450: a hydroxylase, and an oxene transferase, with the former encompassing the classic oxygenase as well as "peroxygenase" reactions.
|Original language||English (US)|
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Mar 31 1981|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology