[Absorption and magnetic circular dichroism spectra of heme proteins in nonequilibrium states. IV. Cytochrome c and its derivatives].

Absorption and magnetic circular dichroism spectra (77 degrees K) of nonequilibrium cytochrome c and its derivatives reduced by thermolysed electrons was studied. The low temperature spectral characteristics of reduced cytochrome c (pH 7.0, 1.6 and 10.0), dimer, carboxymetylated and formylated derivatives at netral and acid pH, also fluoride complexes differ from the characteristics of equilibrium reduced forms. The temperature increase (up to 177 degrees K) induces relaxation of nonequilibrium states. These effects are due to structural differences in the heme vicinity of the reduced and oxidized forms.