Chaperone activities of bovine and camel β-caseins:: Importance of their surface hydrophobicity in protection against alcohol dehydrogenase aggregation

beta-Casein (beta-CN) showing properties of intrinsically unstructured proteins (IUP) displays many similarities with molecular chaperones and shows anti-aggregation activity in vitro. Chaperone activities of bovine and camel beta-CN were studied using alcohol dehydrogenase (ADH) as a substrate. To obtain an adequate relevant information about the chaperone capacities of studied caseins, three different physical parameters including chaperone constant (k(c), mu M-1), thermal aggregation constant (k(T), degrees C-1) and aggregation rate constant (k(1), min(-1)) were measured. Bovine P-CN displays greater chaperone activity than camel P-CN. Fluorescence studies of 8-anilino-1-naphthalenesulfonic acid (ANS) binding demonstrated that bovine P-CN is doted with larger effective hydrophobic surfaces at all studied temperatures than camel P-CN. Greater relative hydrophobicity of bovine beta-CN than camel beta-CN may be a factor responsible for stronger interactions of bovine beta-CN with the aggregation-prone pre denatured molecular species of the substrate ADH, which resulted in greater chaperone activity of bovine P-CN. (c) 2008 Elsevier B.V. All rights reserved.