A. Dussaud et al., SURFACE-PROPERTIES OF PROTEIN ALCOHOLIC SOLUTIONS .1. SURFACE-TENSION, Journal of colloid and interface science, 167(2), 1994, pp. 247-255
The influence of ethanol on protein (e.g., bovine serum albumine (BSA)
) adsorption from aqueous solutions has been investigated by surface t
ensiometry. The surface reaches a quasiequilibrium state resulting fro
m the competitive adsorption of ethanol and BSA molecules. At less tha
n 5%, v/v, ethanol content, kinetics of surface pressure increase resu
lts from the combination of two processes: a fast migration and adsorp
tion that may be enhanced by a change in the state of BSA molecules in
bulk solution (e.g., self-assembling), and a slow increase of surface
pressure possibly caused by protein unfolding at the surface. These e
xperiments made it possible to define a degree of BSA molecules unfold
ing. At 12%, v/v, ethanol content, the surface pressure kinetics displ
ay an overshoot effect. This effect results from the superposition of
three processes: a very fast adsorption of BSA molecules, an irreversi
ble desorption of some adsorbed BSA, and unfolding of the remaining BS
A molecules. (C) 1994 Academic Press, Inc.