Recently, we reported the spectroscopic and kinetic characterizations of cytochrome P450
compound I in CYP119A1, effectively closing the catalytic cycle of cytochrome P450-
mediated hydroxylations. In this minireview, we focus on the developments that made this
breakthrough possible. We examine the importance of enzyme purification in the quest for
reactive intermediates and report the preparation of compound I in a second P450 (P450
ST). In an effort to bring clarity to the field, we also examine the validity of controversial …