Cytochrome P450 Compound Ⅰ

摘要

The cytochromes P450 (P450s) are ubiquitous heme-containing enzymes that effect a vast range of oxidation reactions in nature. By analogy to intermediates formed in other heme-containing enzymes, the putative P450 oxidants are usually thought to be iron(IV)-oxo porphyrin radical cation species termed Compounds Ⅰ. The active oxidants in P450s have been sought since the initial reports of the enzymes in the 1960s, and P450 Compound I has been the Holy Grail of those studies. Transients with millisecond lifetimes can be produced in low conversions by chemical oxidations of P450s, and these short-lived intermediates have been assigned as Compound Ⅰ species. Ironically, typical Compound Ⅰ analogues in models do not display reactivities consistent with those required for the oxidants in P450s, which can hydroxylate an unactivated C—H bond so rapidly that no oxidant accumulates to detectable levels.