Аннотация:Test systems of different kinds are used to characterize the anti-aggregation efficiency of molecular protein chaperones and low-molecular-weight chemical chaperones. Test systems based on aggregation of UV-irradiated proteins are of special interest because such test systems allow studying the protective action of different agents at physiological temperatures. To characterize the changes in the structure of the molecule of glycogen phosphorylase b (Phb) from rabbit skeletal muscle induced by UV radiation, measurements on the enzyme activity, circular dichroism and differential scanning calorimetry were used. The kinetics of UV-irradiated Phb(UV-Phb) was studied at 37°C(0.03 M Hepes buffer, pH 6.8, containing 0.1 M NaCl) usingdynamic light scattering in the wide range of the protein concentrations. It has been shown that the order of aggregation with respect to protein is equal to unity. The conclusion has beenmade that the rate-limiting stage of the overall process of aggregation is the heat-induced structural reorganization of UV-Phb containing concealed damages. The formation of the protein states containing UV-induced concealed damages should be taken into account in studies of the action of ultra violet on biological systems. The study was funded by the Russian Science Foundation (grant number 16-14-10055).