Effect of Arginine on Chaperone-Like Activity of HspB6 and Monomeric 14-3-3ζ.

The effect of protein chaperones HspB6 and the monomeric form of the protein 14-3-3ζ (14-3-3ζ) on a test system based on thermal aggregation of UV-irradiated glycogen phosphorylase (UV-Ph) at 37 °C and a constant ionic strength (0.15 M) was studied using dynamic light scattering. A significant increase in the anti-aggregation activity of HspB6 and 14-3-3ζ was demonstrated in the presence of 0.1 M arginine (Arg). To compare the effects of these chaperones on UV-Ph aggregation, the values of initial stoichiometry of the chaperone-target protein complex () were used. The analysis of the values shows that in the presence of Arg fewer chaperone subunits are needed to completely prevent aggregation of the UV-Ph subunit. The changes in the structures of HspB6 and 14-3-3ζ induced by binding of Arg were evaluated by the fluorescence spectroscopy and differential scanning calorimetry. It was suggested that Arg caused conformational changes in chaperone molecules, which led to a decrease in the thermal stability of protein chaperones and their destabilization.