Dissociative mechanism for irreversible thermal denaturation of oligomeric proteins

Protein stability is a fundamental characteristic essential for understanding conformational transformations of the proteins in the cell. When using protein preparations in biotechnology and biomedicine, the problem of protein stability is of great importance. The kinetics of denaturation of oligomeric proteins may have characteristic properties determined by the quaternary structure. The kinetic schemes of denaturation can include the multiple stages of conformational transitions in the protein oligomer and stages of reversible dissociation of the oligomer. In this case, the shape of the kinetic curve of denaturation or the shape of the melting curve registered by differential scanning calorimetry can vary with varying the protein concentration. The experimental data illustrating dissociative mechanism for irreversible thermal denaturation of oligomeric proteins have been summarized in the present review. The use of test systems based on thermal aggregation of oligomeric proteins for screening of agents possessing anti-aggregation activity is discussed.

Effect of 2-hydroxypropyl-β-cyclodextrin on thermal stability and aggregation of glycogen phosphorylase b from rabbit skeletal muscle

The study of the kinetics of thermal aggregation of glycogen phosphorylase b (Phb) from rabbit skeletal muscles by dynamic light scattering at 48°C showed that 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) accelerated the aggregation process and induced the formation of the larger protein aggregates. The reason of the accelerating effect of HP-β-CD is destabilization of the protein molecule under action of HP-β-CD. This conclusion was supported by the data on differential scanning calorimetry and the kinetic data on thermal inactivation of Phb. It is assumed that destabilization of the Phb molecule is due to preferential binding of HP-β-CD to intermediates of protein unfolding in comparison with the original native state. The conclusion regarding the ability of the native Phb for binding of HP-β-CD was substantiated by the data on the enzyme inhibition by HP-β-CD. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 986-993, 2010.