부산대학교 도서관

The interaction between platelet integrin αllbβ3 and fibrin(ogen) plays a key role in blood clot formation and stability. Integrin antagonists, a class of pharmaceuticals used to prevent and treat cardiovascular disease, are designed to competitively interfere with this process. However, the energetics of the integrin-drug binding are not fully understood, potentially hampering further development of this class of pharmaceuticals. We integrated dynamic force spectroscopy (DFS) and surface plasmon resonance (SPR) to probe the energetics of complex formation between αIIbβ3 and cHarGD, .a cyclic peptide integrin antagonist. Analysis of αIIbβ3:cHarGD DFS rupture force data at pulling rates of 14000 pN/s, 42 000 pN/s and 70000 pN/s yielded koff = 0.02-0.09 s-1, a dissociation energy barrier ΔGd‡ = 22-29kJ/mol, and a potential well width x-1 = 0.5-0.8 nm. SPR kinetic data yielded an association rate constant koff = 7 × 103 L/mol-s and a dissociation rate constant koff = 10-2 s-1, followed by a slower stabilization step (τ ∼ 400 s). Both DFS and SPR detected minimal interactions between αIIbβ3 and cHarGA demonstrating a key role for electrostatic interactions between the ligand aspartate and the integrin metal ion-dependent adhesion site (MIDAS). Our work provides new insights into the energy landscape of αIIbβ3's interactions with pharmacological and physiological ligands. [ABSTRACT FROM AUTHOR]