Substrate interactions in cytochrome P-450: correlation between carbon-13 nuclear magnetic resonance chemical shifts and C-O vibrational frequencies

Abstract13CO NMR chemical shifts and12CO infrared stretching frequencies have been measured for cytochrome P-450camCO in the presence ofd-camphor and of various camphor analogues. A linear correlation between both parametersδ(13C and ν(CO) was found indicating that the steric and electrostatic interactions acting on the CO ligand are influenced by the substrate. It has been proved that P-450 complexes are on another line in this correlation than hemoglobins which is explained by the different proximal ligand