中文摘要：

圆二色谱（CD谱）测量表明，尖吻蝮蛇抗凝血因子Ⅱ（ACFⅡ）与抗凝血因子Ⅰ（ACFⅠ）的二级结构十分相似，它们的主要骨架构象都为反平行β-折叠和α-螺旋结构。pH值对天然ACFⅡ的构象有一定的影响，pH值从3到10增大时，α-螺旋含量逐渐减少，反平行β-折叠含量逐渐增大。钙和其他二价金属离子对ACFⅡ的骨架结构没有明显影响。三价稀土离子使ACFⅡ的α-螺旋含量升高，同时降低其β-转角和β-折叠的含量。

英文摘要：

Anticoagulation factors holo-ACF Ⅱ and holo-ACF Ⅰ have similar secondary structures and their main backbone conformations are anti-parallel β-sheet and α-helix determined by CD spectra. The contents of antiparallel β-sheet and α-helix are 26.2%, 13.7% for holo-ACF Ⅱ, respectively. When pH value increases, the content of α-helix of ACF Ⅱ decreases, while the contents of anti-parallel β-sheet increases. No apparent effects of Ca^2＋, Sr^2＋, Mg^2＋ and transition metal ions （Zn^2＋, Mn^2＋ and Co^2＋） on conformations of the backbone of ACF Ⅱ are observed. The substitution of lanthanide ions for Ca^2＋ in ACF Ⅱ increases the content of α-helix, but decreases the content of β-sheet.