尖吻蝮蛇毒中抗血小板凝集素是凝血因子Ⅸ/凝血因子Ⅹ结合蛋白,它具有抗凝血和抑制血小板凝集双重活性.用红外光谱、拉曼光谱和CD谱研究了抗血小板凝集素的二级结构以及pH值和钙离子对其二级结构的影响.用CD谱测得,在水溶液中,抗血小板凝集素的主要骨架构象为β-折叠(26.3%)和α-螺旋(19.6%)结构.拉曼光谱显示,在粉末状态,其α-螺旋含量显著降低.CD谱还表明,抗血小板凝集素在pH值3.0～11.0范围内保持稳定的天然结构,钙离子诱导的抗血小板凝集素结构变化是可逆的,钙离子在稳定抗血小板凝集素的天然结构中起重要作用.%Agkisacutacin isolated from the venom of Agkistrodon acutus is a coagulation factor Ⅸ/coagulation factor Ⅹ-binding protein with marked anticoagulant- and platelet-modulating activities. The effects of pH value and Ca2+ ion on the secondary structure of Agkisacutacin have been studied by FTIR, Raman and circular dichroism (CD) spectroscopy. The main backbone conformations of holo-Agkisacutacin are α-helix (19.6%) and β-sheet (26.3%) as determined by CD spectroscopy. According to the Raman measurements, the content of α-helix of holo-Agkisacutacin in solid powder is less than that in solution. The conformation of Agkisacutacin is stable in the pH range of 3.0～11.0 as shown by CD spectroscopy. Ca2+-induced conformation change of Agkisacutacin is reversible. Ca2+ ion plays an important role in the stabilization of the structure of Agkisacutacin.
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