Amino acid sequence of fibrolase, a direct‐acting fibrinolytic enzyme from agkistrodon contortrix contortrix venom
Amino acid sequence of fibrolase, a direct‐acting fibrinolytic enzyme from agkistrodon contortrix contortrix venom
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DOI：
10.1002/pro.5560010505
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发表时间：
1992-05
期刊：
影响因子：
8
通讯作者：
A. Randolph;S. Chamberlain;H. Chu;F. Masiarz;A. Retzios;F. Markland
中科院分区：
文献类型：
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作者：
A. Randolph;S. Chamberlain;H. Chu;F. Masiarz;A. Retzios;F. Markland
测定了蛇毒纤溶酶的氨基酸全序列。这是在蛇毒中发现的一种直接作用、非出血性纤溶酶序列的首次报告。该序列的大部分是通过对由各种选择性切割程序产生的重叠多肽进行自动埃德曼降解而建立的。氨基末端被环化的谷氨酰胺(焦谷氨酸)残基封闭，并用质谱仪测定了分子这一区域的序列。纤维素酶是由203个残基组成的单一多肽链，分子量为22,891，由序列确定。其序列与乌鸦蛇毒出血性毒素Ht-d的序列同源，与黄绿色Trimeresurus黄绿色蛇毒两种金属蛋白酶的序列同源。在该序列的氨基末端以及第189和192位残基上都发现了微观异质性。纤维素酶中的六个半胱氨酸残基都与二硫键有关。根据与Ht-d的同源性，半胱氨酸-118和半胱氨酸-198之间建立了二硫键，半胱氨酸-15 8/16 5和半胱氨酸-16 0/192之间存在键。二级结构预测显示α-螺旋的比例很低(4%)，但β-结构的比例要高得多(39.5%)。对该序列的分析表明，天冬酰胺连接的糖基化位点不存在由共同序列：天冬酰胺-X-丝氨酸/苏氨酸定义。
The complete amino acid sequence of fibrolase, a fibrinolytic enzyme from southern copperhead (Agkistrodon contortrix contortrix) venom, has been determined. This is the first report of the sequence of a direct‐acting, non‐hemorrhagic fibrinolytic enzyme found in snake venom. The majority of the sequence was established by automated Edman degradation of overlapping peptides generated by a variety of selective cleavage procedures. The amino‐terminus is blocked by a cyclized glutamine (pyroglutamic acid) residue, and the sequence of this region of the molecule was determined by mass spectrometry. Fibrolase is composed of 203 residues in a single polypeptide chain with a molecular weight of 22,891, as determined by the sequence. Its sequence is homologous to the sequence of the hemorrhagic toxin Ht‐d of Crotalus atrox venom and with the sequences of two metalloproteinases from Trimeresurus flavoviridis venom. Microheterogeneity in the sequence was found at both the amino‐terminus and at residues 189 and 192. All six cysteine residues in fibrolase are involved in disulfide bonds. A disulfide bond between cysteine‐118 and cysteine‐198 has been established and bonds between cysteines‐158/165 and between cysteines‐160/192 are inferred from the homology to Ht‐d. Secondary structure prediction reveals a very low percentage of α‐helix (4%), but much greater β‐structure (39.5%). Analysis of the sequence reveals the absence of asparagine‐linked glycosylation sites defined by the consensus sequence: asparagine‐X‐serine/threonine.