Observation of structural variation and spin state conversion of cytochrome P450 CYP2B4 on binding of sterically...

Addition of sterically different substrates to CYP2B4 suggests perturbation of the environment of the haem ring and differing degrees of 6cls-5chs conversion. Strain on the ring, by implication induced by changes in the surrounding protein environment, is demonstrated by the emergence of the v29 band upon laurate binding. Furthermore, intensity differences and frequency shifts for non-Raman active (Eu) modes appear to be substrate dependent and are sensitive to haem/substrate interactions. The likelihood is that substrate induced distortion of the haem will have an effect on catalytic activities and attention needs to be directed towards substrate pocket interactions. SERRS (Surface enhanced resonance Raman scattering) provides a unique and sensitive spectroscopic probe of these interactions.