Resonance Raman study of the cytochrome P‐450 LM2‐halothane intermediate complex

Abstract
Resonance Raman (RR) and absorption spectroscopic studies of purified rabbit liver cytochromes P‐450 show that the form 2 isomer (LM2) but not the form 4 isomer (LM4) forms a long‐lived complex with halothane after dithionite reduction, absorbing light at 470 nm, in which ferric 6‐coordinated heme iron in the low‐spin configuration is liganded to 2‐chloro‐1,1‐difluoroethylene. The RR data exclude the possibility that the CF3CHCl carbanion is a ligand and are consistent with the involvement of an active‐site pocket in the cytochrome P‐450 polypeptide.