We analyzed the vibrational frequencies of the Fe-bound carbon monoxide (CO) of myoglobin reconstituted with a series of chemically modified heme cofactors possessing a heme Fe atom with a variety of electron densities. The study revealed that the stretching frequency of Fe-bound CO (νCO) increases with decreasing electron density of the heme Fe atom (ρFe). This finding demonstrated that the νCO value can be used as a sensitive measure of the ρFe value and that the π back-donation of the heme Fe atom to CO is affected by the heme π-system perturbation induced through peripheral side chain modifications.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry