This project will attempt to relate the rate or extent of surface- induced conformational changes in adsorbed proteins to their equilibrium adsorbed mass by in situ ellipsometry. Equilibrium isotherms of alpha-lactalbumin, beta-lactoglobulin, and kappa-casein on germanium will be evaluated. Then, the influence of time on conformational changes experienced by these proteins will be quantified by continuously monitoring the film thickness by ellipsometry. It is now well known that high-molecular weight proteins can be damaged by their interactions with surfaces. The extent of damage seems to be time-dependent. It is hypothesized that this damage occurs as the protein unfolds to bring more of its surface into contact with regions of the surface to which they are attracted. This phenomenon is important to both biomedical technology and downstream processing in biotechnology. If the protein unfolds as it interacts progressively strongly with the surface, it seems reasonable to expect the apparent thickness of a film of adsorbed protein to decrease with time and for the amount of damage to correlate with the film thickness. This project will test that hypothesis and lead to a better understanding of the phenomenon and its dynamics.
