Kinetics of thermal aggregation of glycogen phosphorylase b from rabbit skeletal muscle: mechanism of protective action of alpha-crystallin.
The kinetics of thermal aggregation of glycogen phosphorylase b (Phb) from rabbit skeletal muscle have been studied by dynamic light scattering (0.08M Hepes, pH 6.8, containing 0.1M NaCl; 48 degrees C). The hydrodynamic radius of the start aggregates determined from the initial linear parts of the dependences of the hydrodynamic radius (R(h)) on time was found to be 16.7 +/- 1.0 nm. At rather high values of time, the R(h) value for the protein aggregates becomes proportional to t(1/1.8) = t(0.56) suggesting that the aggregation process proceeds in the regime of diffusion-limited cluster-cluster aggregation. In the presence of alpha-crystallin, a protein possessing the chaperone-like activity, the process of protein aggregation switches to the regime of reaction-limited cluster-cluster aggregation as indicated by the exponential dependence of the R(h) value on time. It was shown that the addition of alpha-crystallin raises the rate of thermal inactivation of Phb. These data in combination with the results of the study of interaction of Phb with alpha-crystallin by analytical ultracentrifugation suggest that alpha-crystallin interacts with the intermediates of unfolding of the Phb molecule.
Meremyanin
Alexey V
AV
A.N. Bakh Institute of Biochemistry, Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia. mer-av@inbi.ras.ru
Eronina
Tatyana B
TB
Chebotareva
Natalia A
NA
Kurganov
Boris I
BI
D000818:Animals; D004058:Diffusion; D024982:Glycogen Phosphorylase, Muscle Form / Q000737:chemistry*; D006358:Hot Temperature; D007700:Kinetics; D008956:Models, Chemical; D015233:Models, Statistical; D008968:Molecular Conformation; D018482:Muscle, Skeletal / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011817:Rabbits; D012542:Scattering, Radiation; D038201:alpha-Crystallins / Q000737:chemistry*
D011108:Polymers; D038201:alpha-Crystallins; D024982:Glycogen Phosphorylase, Muscle Form