Resonance Raman Spectra of Cobalt-Substituted Hemoglobin: Cooperativity and Displacement of the Cobalt Atom upon Oxygenation

摘要: Abstract The resonance Raman spectra of oxy and deoxy cobalt-substituted hemoglobin (CoHb) are reported. Comparison these to those hemoglobin, methemoglobin, cytochrome c, model cobalt porphyrin complexes suggests that the displacement atom upon oxygenation CoHb is no greater than out-of-plane distance in five-coordinate Co(II) porphyrins, 0.15 A. Combining this with expected contraction cobalt-histidine bond, Ibers has estimated a maximum 0.37 A for proximal histidine respect heme plane oxygenation, about one-third corresponding iron hemoglobin. The free energy cooperativity also be These results therefore consistent Hopfield's distributed model, which predicts proportionality between cooperativity. By implication they support Perutz's trigger mechanism