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Murine tetrameric oxyhaemoglobin and insect monomeric erythrocruorin were studied. A doublet with the Lorentz form of lines (delta EQ = 2.22 mm s-1; delta alpha-Fe = 0.27 mm s-1; gamma 1/2 = 0.29 mm s-1) was observed in the oxyhaemoglobin spectrum at 4.2 K. In the 80-170 K interval the doublet components are distorted, but at T greater than 175 K, the lines again become symmetrical. In the 175-210 K region the value of gamma 1/2 is approximately 0.42 mm s-1. The profiles of the oxyhaemoglobin spectra are not dependent on the nature of the samples (blood; whole, or in aqueous or water-glycerol solutions at different pH values), or on the rate at which the latter are frozen. The oxyerythrocruorin spectra in aqueous solution and in a water-glycerol solution at 80 K and 170 K were doublets with Lorentz lines (the delta EQ values are equal to 2.20 mm s-1 and 2.12 mm s-1, respectively). It is concluded that the characteristics of the oxyhaemoglobin spectra reflect the specific electronic and structural properties of the oxy-complex in this protein. It was found that the oxyhaemoglobin spectra are very adequately described by two doublets with equal delta and gamma 1/2 values, but with different delta EQ values and relative intensities. A model is described in which these doublets correspond to two types of hydrogen bond associated with the distal histidine (E7), involving the terminal atom of molecular oxygen and the oxygen atom bound with the haem iron, respectively.

Nonequilibrium hemoglobin states formed at low-temperature (T = 77K) reduction of its derivatives (MetHb and HbO2) by thermolysed electrons have been studied by Mössbauer spectroscopy. Relaxation of nonequilibrium states at the samples heating was observed. Correlation between the relaxation temperatures and the changes of protein dynamic structure determined from Mössbauer data were stated.