Direct Observation of Antifreeze Glycoprotein-Fraction 8 on Hydrophobic and Hydrophilic Interfaces Using Atomic Force Microscopy

Abstract

The adsorption of antifreeze glycoprotein-fraction 8 (AFGP 8) was studied via a drop deposition method onto hydrophobic (HOPG) and hydrophilic (mica) surfaces. On HOPG, preferential adsorption occurred at the hydrophilic step edges with homogeneous nucleation on hydrophobic planes. Individual particle sizes are consistent with aggregates, and the uniform size of these particles suggests aggregation is a preadsorption event. The adsorption of AFGP 8 onto hydrophilic mica was also consistent with aggregates of individual molecules. Adsorption studies of other glycosylated and nonglycosylated proteins suggest that not only is the adsorption event onto different surfaces influenced by glycosylation but also secondary and tertiary protein structure may play a critical role.