The adsorption of antifreeze glycoprotein fraction 8 on dry and wet mica

The adsorption of AFGP 8 on mica was studied by atomic force microscopy. The results shown in this paper emphasize the strong adsorption affinity of these proteins to hydrophilic surfaces, in this case mica. The dependence of the surface morphology while drying a droplet of protein solution, and the tendency to form 3-D aggregates at high concentration was observed. The behavior indicates that single-molecule-high aggregates (8.1 Å) are formed at low concentration; as the concentration increases, a double layer seems to appear in equilibrium with large aggregates; and as the concentration is increased further, the equilibrium is shifted toward larger aggregates leaving behind residual single-molecule-high aggregates. The hydrophilicity of the protein was demonstrated by the spontaneous adsorption of the protein directly from solution, as monitored by in situ imaging.