The resonance Raman frequencies of the Fe-CO stretching and bending modes in the CO complex of cytochrome P-450cam.

Resonance Raman spectra of the ferrous CO complex of cytochrome P-46Ocam have been observed both in its camphor-bound and free states.Upon excitation at 467.9 nm, near the absorption maximum of the Soret band, the ferrous CO complex of the camphor-bound enzyme showed an anomalously intense Raman line at 481 cm" besides the strong Raman lines at 1366 and 674 cm" for the porphyrin vibrations.The Raman line at 481 cm-' (of the "C"0 complex) shifted to 478 cm" upon the substitution by 'sC'60 and to 473 cm" by 12C'80 without any detectable shift in porphyrin Raman lines.This shows that the line at 481 cm" is assignable to Fe-CO stretching vibration.By the excitation at 467.9 nm, a weak Raman line was also observed at 668 cm", which was assigned to the Fe-C-0 bending vibration, because it was found to shift by -14 C 0 substitution while only -3 cm" on 12C's0 substitution.These stretching and bending vibrations of the Fe-CO bond were not detected with the excitation at 413.1 nm, though the porphyrin Raman lines at 1366 and 674 cm" were clearly observed.When the substrate, camphor, was removed from the enzyme, the Fe-CO stretching vibration was found to shift to 464 cm" from 481 cm", while no detectable changes were found in porphyrin Raman lines.This means that the bound substrate interacts predominantly with the Fe-CO portion of the enzyme molecule. cm-l on 13 16Cytochrome P-450 is a generic name given to a group of protoheme-containing hemoproteins which give rise to the absorption maximum near 450 nm upon the formation of CO adduct (1, 2).This type of hemoprotein has been recognized as a monooxygenase functional in the metabolic transformation reactions in living organisms.Cytochrome P-450cam,' a member of the cytochrome P-4508, was found in Pseudomonas putida grown on D-camphor