Structural perturbation of αB-crystallin by zinc and temperature related to its chaperone-like activity

αB-crystallin is a small heat shock protein that shows chaperone-like activity, as it protects the aggregation of denatured proteins. In this work, the possible relationships between structural characteristics and the biological activity of αB-crystallin were investigated on the native protein and on the protein undergoing the separate effects of metal ligation and temperature. The chaperone-like activity of αB-crystallin increased in the presence of zinc and when temperature was increased. By using fluorescent probes to monitor hydrophobic surfaces on αB-crystallin, it was found that exposed hydrophobic patches on the protein surface increased significantly both in the presence of zinc and when the temperature was raised from 25 to 37 °C. The zinc-induced increased exposure of lipophilic residues is in agreement with theoretical calculations performed on 3D-models of monomeric αB-crystallin, and may be significant to its increased biological activity.