Orientation of the water molecules of hydration of human serum albumin

Abstract

Through contact-angle measurements with a number of liquids, on layers of hydrated human serum albumin (HSA), built on anisotropic ultrafilter membranes, the apolar, Lifshitz-van der Waals surface tension component, as well as the polar, electron-acceptor and electron-donor parameters of the hydrated layers could be determined. From these data, it was found that the degree of orientation of the water molecules of hydration of HSA is ≈98% in the first layer of hydration and ≈30% of the second layer. The water molecules of hydration are oriented with the H atoms closest to, and the O atoms farthest from, the protein surface.