Kinetic regime of thermal aggregation of holo- and apoglycogen phosphorylases b

Abstract

To characterize the role of pyridoxal 5⿲-phosphate in stabilization of the conformation of muscle glycogen phosphorylase b (Phb), the mechanism of thermal aggregation for holo- and apoforms of Phb has been studied using dynamic light scattering. The order of aggregation with respect to the protein (n) for aggregation of holoPhb at 48°C is equal to 0.5 suggesting that the dissociative mechanism of denaturation is operative and denaturation is followed by rapid aggregation stage. In the case of aggregation of apoPhb at 37°C n=2 and the rate-limiting stage is aggregation of unfolded protein molecules.