Resonance Raman spectra of deoxyhemoproteins. Heme structure in relation to dioxygen binding

The low-frequency regions of the resonance Raman spectra of deoxygenated ferrous forms of soybean leghemoglobin $\text{a}$, horse myoglobin, sperm whale myoglobin, Aplysia myoglobin, stripped normal human hemoglobin (T quaternary form) and of stripped human NESdesArg-hemoglobin (R quaternary form) are reported. Differences observed among these spectra show that the globins of these hemoproteins impose various heme structures. In particular, the variable frequencies of band II (210–224 cm⁻¹) and of band I_b (121–163 cm⁻¹) show that an increase in dioxygen affinity corresponds to a decrease in Fe-N(pyrrole) bond length.