A resonance Raman study of the binding of ethanol and methanol to ferrihemoglobin

The interactions of ethanol and methanol with ferrihemoglobin were examined using resonance Raman spectroscopy. After binding either alcohol, the low-frequency resonance Raman spectra of human ferrihemoglobin are almost identical to the unperturbed spectrum except for shifts in the 309 cm-1 band to higher frequency by as much as 8 cm-1. The ethanol-induced shift is greater than that with methanol even though complex formation was less for ethanol than methanol. The spectral changes imply a site-specific, similar binding of these alcohols to ferrihemoglobin which may involve steric interactions. Possible assignments of the 309 cm-1 band to structural features as well as potential mechanisms of the alcohol-induced spectral changes are discussed.