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

β-Casein (β-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 β-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 (kc, μM−1), thermal aggregation constant (kT, °C−1) and aggregation rate constant (kt, min−1) were measured. Bovine β-CN displays greater chaperone activity than camel β-CN. Fluorescence studies of 8-anilino-1-naphthalenesulfonic acid (ANS) binding demonstrated that bovine β-CN is doted with larger effective hydrophobic surfaces at all studied temperatures than camel β-CN. Greater relative hydrophobicity of bovine β-CN than camel β-CN may be a factor responsible for stronger interactions of bovine β-CN with the aggregation-prone pre denatured molecular species of the substrate ADH, which resulted in greater chaperone activity of bovine β-CN.