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尖吻蝮蛇毒抗凝血因子I(ACFI)是活化凝血因子X(FXa)结合蛋白,具有显著的抗凝血活性.用荧光光谱研究了Sr2+诱导ACFI的结构稳定性及重新折叠.结果表明,脱钙ACFI(apo-ACFI)可结合两个Sr2+.ACFI与FXa的结合反应不是绝对依赖于Ca2+,Sr2+也可以诱导ACFI与FXa的结合反应.盐酸胍诱导的Sr2+重组ACFI(Sr2+-ACFI)去折叠过程是一个三态过程,有一个稳定的中间态.像Ca2+一样,Sr2+不仅能显著增加ACFI的结构稳定性,而且在不改变变性剂浓度条件下,能诱导去折叠的脱钙ACFI重新折叠成Sr2+-ACFI的中间态.Sr2+诱导apo-ACFI重新折叠过程包含快慢两步反应,Sr2+取代Ca2+只降低快折叠反应速度,而不影响慢折叠反应速度.这说明,金属离子影响快折叠过程,而慢折叠过程只决定于蛋白质本身性质.
ACFI is an activated coagulation factor X (FXa) -binding protein with significant anticoagulant activity.The structural stability and refolding of ACFI induced by Sr2 + were studied by fluorescence spectroscopy.The results showed that the ACFI- The decarboxylation of ACFI (apo-ACFI) can bind to two Sr2 + .The reaction of ACFI with FXa is not dependent on Ca2 +, Sr2 + can also induce the binding reaction of ACFI with FXa.Guangidine hydrochloride induced Sr2 + recombinant ACFI (Sr2 + -ACFI) The folding process is a three-state process with a stable intermediate state. Like Ca2 +, Sr2 + not only significantly increases the structural stability of ACFI but also induces deffolded decalcified ACFI to refold without changing the denaturant concentration Sr2 + -ACFI intermediates.Sr2 induced apo-ACFI refolding process contains two steps of fast and slow reaction, Sr2 + Ca2 + only to reduce the speed of fast folding reaction without affecting the slow folding reaction rate.This shows that metal ions affect the fast folding process, The slow folding process only depends on the nature of the protein itself.