Assignment of protoheme resonance Raman spectrum by heme labeling in myoglobin

The resonance Raman (RR) spectra of myoglobin reconstituted with seven heme isotopomers was assigned to determine how the oxidation and ligation states of myoglobin affect the structure of its noncovalently bound protoheme group. The assignments were facilitated by labeling the hemes with 15N and meso-D4 at the site of the vinyl and propionate substituents or in the porphyrin backbone. The results demonstrated protein-specific effects via the activation of several out-of-plane modesin the low frequency band of the RR spectra.