3-DIMENSIONAL STRUCTURE OF HUMAN FIBRINOGEN UNDER AQUEOUS CONDITIONS VISUALIZED BY ATOMIC-FORCE MICROSCOPY

Fibrinogen plays a central role in surface-induced thrombosis. However , the interactions of fibrinogen with different substrata remain poorl y understood because of the difficulties involved in imaging globular proteins under aqueous conditions. We present detailed three dimension al molecular scale images of fibrinogen molecules on a hydrophobic sur face under aqueous conditions obtained by atomic force microscopy. Hyd rated fibrinogen monomers are visualized as overlapping ellipsoids: di mers and trimers have linear conformations predominantly, and increase d affinity for the hydrophobic surface compared with monomeric fibrino gen. The results demonstrate the importance of hydration on protein st ructure and properties that affect surface-dependent interactions.