PROTEIN INTERACTIONS AT SOLID-SURFACES

In this review article we discuss a large number of the studies of int eractions between protein-coated surfaces that has been presented in t he literature. We also demonstrate how to relate surface force data to results from other techniques in order to provide a more full picture of protein behaviour at interfaces. One aim of the article is to disc uss the experimental procedure and the difficulties with surface force measurements in protein systems. It is particularly important to poin t out how the sensitivity of this technique differs from that of other techniques, e.g. in determining structural changes in adsorbed protei ns and in detecting proteins adsorbed on top of an inner firmly bound layer. It is also important to realize which surface force data cannot easily be compared with findings from other techniques (one example i s the kinetics of adsorption and desorption). We have tried to group p roteins into different classes depending on their size and structure, and to try to find results that are common within these classes. It wa s found that some observations for unordered proteins with amphiphilic character, and for the small compact proteins, appear consistently wi thin the respective class. Hence, for these types of protein common fe atures/principles of the interfacial behaviour are identified. The ver y large and flexible glycoproteins behave in a similar way to syntheti c polymers, but we found it hard to draw any firm conclusions based on the surface force studies presented so far. Perhaps, the most complic ated surface behaviour is observed for soft globular proteins that und ergo large-scale conformational changes upon adsorption and when the l ayers are held under a high compressive force.