[Theory of the Mössbauer effect in proteins].

Specific features of the Mössbauer effect on proteins are discussed. A sharp decrease in f' (T) at temperature above 200 degrees K that was found is due to the specificity of conformational mobility of proteins and due to a smaller correlation time for spacially--confined diffusion of a Mössbauer label tracer below a critical value of tau approximately 10(-7) s (the lifetime of 57Fe excitation). Protein conformational mobility is described by a Brownian strongly damped oscillator. For this model, a new formula for the Mössbauer effect probability is derived. Calculations by the formula and corresponding experimental data are in good accord. By the formula for f' (T), a theoretical temperature dependence of medium microviscosity (with an activation energy of 5 kcal/mol) and estimates for some parameters are obtained.