A novel method of determination of protein stability.

A novel method of determination of protein stability is described, which involves interfacial shear rheology of adsorbed protein layers. This technique provides information on the structural-mechanical properties of the adsorbed protein layers which can be related to: the rate of interfacial adsorption, interfacial interactions, and conformational changes in the adsorbed layers. The interfacial shear rheology of the blood proteins, bovine serum albumin and human immunoglobulin G was investigated. The air/aqueous and oil/aqueous interfaces were studied and the interfacial rheological activity of BSA was shown to be similar at three hydrophobic interfaces: air, squalene and mineral oil. The kinetics of interfacial film formation was shown to be time dependent, and aging effects were detected in both interfacial and bulk molecules. The absolute interfacial elasticity values decreased as the temperature increased. The protein solutions exhibited no interfacial rheological activity in the presence of the small surfactant molecules, Tween 80 and lecithin, under the conditions studied.