[ESR study of the superslow diffusion of lysozyme macroradicals in an aqueous matrix]

Using kinetic data on recombination macroradicals in freezed water solutions of lyzozyme, superslow molecular motions of biopolymer have been studied. Recombination of macroradicals is observed at 160--240 K and it has a stepwise character. The kinetic data are described quantitatively by the model, in which the set of processes with different rate constants is considered (the so-called model of polychromatic kinetics). It has been shown that polychromatic character of the process is conditioned by energy activation distribution, which is changed from Emin = 8+/-1 kcal/mol to Emax = 13 +/- 1 kcal/mol with "rectangular" distribution function f(E) approximately equal to: formula: (see text). Preexponential factor K0 = 2 . 10 (-9)cm3.s-1. The recombination-kinetic method used permits to estimate frequencies (inverse correlation time) translation mobility macroradicals of protein up to the frequency order 10(-2)s-1 (or velocities of motions approximately 1 A/s).