Thermodynamic Analysis of the Interaction of Factor VIII with von Willebrand Factor

详细信息    查看全文

• 作者：Jordan D. Dimitrov ; OlivierD. Christophe ; Jonghoon Kang ; Yohann Repess茅 ; Sandrine Delignat ; Srinivas V. Kaveri ; S茅bastien Lacroix-Desmazes
• 刊名：Biochemistry
• 出版年：2012
• 出版时间：May 22, 2012
• 年：2012
• 卷：51
• 期：20
• 页码：4108-4116
• 全文大小：363K
• 年卷期：v.51,no.20(May 22, 2012)
• ISSN：1520-4995

文摘

Factor VIII (FVIII) is a glycoprotein that plays an important role in the intrinsic pathway of coagulation. In circulation, FVIII is protected upon binding to von Willebrand factor (VWF), a chaperone molecule that regulates its half-life, distribution, and activity. Despite the biological significance of this interaction, its molecular mechanisms are not fully characterized. We determined the equilibrium and activation thermodynamics of the interaction between FVIII and VWF. The equilibrium affinity determined by surface plasmon resonance was temperature-dependent with a value of 0.8 nM at 35 掳C. The FVIII鈥揤WF interaction was characterized by very fast association (8.56 脳 10⁶ M^鈥? s^鈥?) and fast dissociation (6.89 脳 10^鈥? s^鈥?) rates. Both the equilibrium association and association rate constants, but not the dissociation rate constant, were dependent on temperature. Binding of FVIII to VWF was characterized by favorable changes in the equilibrium and activation entropy (T螖S掳 = 89.4 kJ/mol, and 鈥?i>T螖S = 鈭?.9 kJ/mol) and unfavorable changes in the equilibrium and activation enthalpy (螖H掳 = 39.1 kJ/mol, and 螖H = 44.1 kJ/mol), yielding a negative change in the equilibrium Gibbs energy. Binding of FVIII to VWF in solid-phase assays demonstrated a high sensitivity to acidic pH and a sensitivity to ionic strength. Our data indicate that the interaction between FVIII and VWF is mediated mainly by electrostatic forces, and that it is not accompanied by entropic constraints, suggesting the absence of conformational adaptation but the presence of rigid 鈥減re-optimized鈥?binding surfaces.