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

alpha B-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 alpha B-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 alpha B-crystallin increased in the presence of zinc and when temperature was increased. By using fluorescent probes to monitor hydrophobic surfaces on alpha B-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 degrees C. The zinc-induced increased exposure of lipophilic residues is in agreement with theoretical calculations performed on 3D-models of monomeric alpha B-crystallin, and may be significant to its increased biological activity. (C) 2007 Elsevier B.V. All rights reserved.