[Absorption and magnetic circular dichroism spectra of nonequilibrium states of hemoproteins. II. Myoglobin and its complexes].

Absorption and magnetic circular dichroism spectra of non-equilibrium states of myoglobin and its complexes formed by reduction oxidased forms of proteins by thermalysed electrons at 77 degrees K were studied. Mixtures of high spin and low spin ferroforms were observed for nonequilibrium states of myoglobin and its complex with fluorine, the content of the high spin form is larger in the complex. Two intense peaks were found in the alpha-band region of absorption spectra of myoglobin and its spectra with F-, OH- and imidazole. This effect is due to lowering of the active centre's symmetry. Similarity of spectral characteristics of low spin ferroforms of these complexes was explained by the strong influence of distal histidine. The low temperature reduction of azide and cyanide complexes of myoglobin led to formation of nonequilibrium low spin ferroforms whose spectra demonstrate the presence of N3- and CN- in heme iron's coordination sphere. The temperature relaxation of all nonequilibrium systems were investigated.