Hemoglobin Heme Conformation in Patients with Different Oxygen Saturation Values

The characteristics of prosthetic group of hemoglobin – heme at different values of the oxygen saturation (sO2) was studied in human whole blood of patients with various clinical forms of coronary heart disease using the method of Raman spectroscopy. Correlation between the values of ratios of Raman spectra bands (1375 and 1355 & 1588 and 1552 cm–1, correspondingly) and oxygen saturation was shown. Based on the analysis of the Raman spectra, it is directly shown that at low sO2 the streatching of the heme ring comes before the binding of the bivalent iron atom to the oxygen molecule. It is probably caused by the cooperative effect (the attachment of a ligand to one heme leads to a change in of the protein and therefore the conformations of other hemes without ligands).