結合蛋白是一群位於細胞表面的蛋白質，能與細胞外間質有交互作用，這作用控制細胞生長、分化與遷移，牽涉到許多疾病的進程。結合蛋白alphaIIb beta3是大量表現於血小板表面的醣蛋白，能與血槳中在血栓形成及止血作用有重要角色的血纖維蛋白原結合。這樣的結合可以被含有RGD (Arg-Gly-Asp)序列的去結合蛋白所抑制。去結合蛋白是在蛇毒中發現的一群血小板抑制劑。它們是可溶於水的短peptide，長度從47至84個胺基酸並且具有一個RGD環，含有4到7對雙硫鍵。我們使用的去結合蛇毒蛋白(Rho)是從馬來蝮蛇蛇毒中純化出來，可阻斷血纖維蛋白和血小板上結合蛋白的結合來抑制血小板的凝集。Rho為68個胺基酸含有六對雙硫鍵以及在序列49到51的RGD的胺基酸序列。我們利用核磁共振(NMR)與抑制血小板功能測定發現由酵母菌所表現出的Rho重組蛋白具有正確的摺疊(folding)與功能。重組Rho的百分之五十抑制濃度(IC50)是78nM，和天然的Rho蛋白的效率相近，而若將RGD的D突變成E (Glu)，則活性下降了863倍以上。為了要解釋樣巨大的活性下降情形，我們使用了圓二色旋光和核磁共振光譜儀來決定他們在結構的折疊上有無差別。根據我們利用NMR判定的結果，我們解出Rho及其D51E突變株的三度空間結構。由結構看來，與結合蛋白結合的RGD/E motif位於一個被一組反平行(anti-parallel)beta-sheet夾出來的9個胺基長的環(loop)。而這個RGD/E環是從蛋白質的核心(core)向外伸出，並且RGD/E的序列位於這個環的頂端以RG[D/E]M四個胺基酸形成type-I turn。但是Rho和D51E突變株在三級結構上並無明顯差異，僅在帶正電的R49及帶負電D51或E51之間的電性分離程度有些微差異。我們推測這樣因為突變造成的活性差異可能是來自於，去結合蛋白和結合蛋白交互作用的機構不同所造成。另外我們也利用NMR研究Rho的動力學。

Integrins are the principal family of cell surface proteins that interact with the extracellular matrices. These interactions control the adhesion and migration of cells, as well as the transduction of signals that regulate cell growth and differentiation. Integrin alphaIIb beta3, a platelet membrane glycoprotein, binds to fibrinogen that plays an important role in thrombosis and hemostasis. The interaction between integrin alphaIIb beta3 and fibrinogen could be inhibited by disintegrins in an RGD (Arg-Gly-Asp)-dependent mechanism.
Snake venom disintegrins are a family of platelet aggregation inhibitors. They are short soluble peptides ranging from 47 to 84 amino acids with an RGD loop containing 4-7 disulfide bonds. Rhodostomin (Rho) is a snake venom protein isolated from Calloselasma rhodostoma. Rho is disintegrin which inhibits platelet aggregation by blocking the binding of fibrinogen to the integrin alphaIIb beta3 of platelets. Rho consists of 68 amino acids including six disulfide bonds and an RGD sequence at position 49-51. The recombinant Rho produced in Pichia pastoris inhibits the platelet aggregation with a KI of 70nM that is potent as native Rho. However, its D51E mutant inhibits the platelet aggregation with a KI of 50M. In order to understand what causes an 863-fold decrease in activity, circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy were used to determine the structural differences in the tertiary folds of Rho and its D51E mutant. By NMR studies, we have determined the 3D structures of Rho and its D51E mutant. The binding site for integrin, lies in a nine-residue loop joining two strands of beta-sheet. The RGD/E loop extends outward from the protein core with the RGD/E sequence at its apex in a four-residue (RGD/EM) type I turn. The only difference in their structures is the charge separation between positive (R49) and negative residues (D/E51). We also use NMR to study the dynamics of Rho.

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