Single-molecule measurement and bioinformatics analysis suggest a preferred orientation of human coagulation factor...

Investigating the adsorption behavior of coagulation proteins on interfaces will contribute to better understating blood clotting and to the development of biocompatible materials. In this work, atomic force microscopy (AFM)-based peakforce quantitative nanomechanical mapping (PF-QNM) was combined with bioinformatics tool to study the adsorption and orientation of coagulation factor VIII (FVIII) on both hydrophilic and hydrophobic interfaces by the height and mechanical measurement of single protein molecules. We found that interfacial hydrophilicity/hydrophobicity greatly influence the heights and Young's modulus of individual proteins. Compared to on the hydrophilic mica surface, FVIII proteins appear bigger vertical sizes while similar lateral sizes on the HOPG surface. The water accessible surface area analysis indicate stronger apolar properties C1 and C2 domains than others, suggesting a preferred orientation through the strong hydrophobic interactions between HOPG and the hydrophobic residues interface of the protein domains. These results provide novel insights on the adsorption and binding mechanism of the FVIII on cell membrane and will be helpful for the design of anticoagulant materials.