Atoda H, Morita T
Department of Biochemistry, Meiji College of Pharmacy, Tokyo.
J Biochem. 1993 Feb;113(2):159-63. doi: 10.1093/oxfordjournals.jbchem.a124020.
Blood coagulation factor IX/factor X-binding protein (IX/X-bp) is a two-chain anticoagulant protein that was isolated from the venom of Trimeresurus flavoviridis. The amino acid sequence of IX/X-bp is homologous to the sequences of C-type lectin-like proteins, such as asialoglycoprotein receptor, tetranectin, and the low-affinity Fc epsilon receptor of immunoglobulin E. The amino acid composition and amino acid sequence of cystine-containing peptides, formed as a result of enzymatic digestion of CNBr-generated fragments of IX/X-bp, were analyzed to determine the location of the seven disulfide bridges in the protein. Three disulfide bridges in the A chain link Cys2 to Cys13, Cys30 to Cys127, and Cys102 to Cys119. Three disulfide bridges in the A chain link Cys2 to Cys13, Cys30 to Cys119, and Cys96 to Cys111. An interchain disulfide bond links Cys79 of the A chain and Cys75 of the B chain. The intrachain disulfide-bonding patterns of both the A and B chains of IX/X-bp are similar to those found in other C-type lectin-like proteins. We discuss in this report the sequence homology between IX/X-bp and other two-chain, C-type lectin-like proteins that have been isolated from snake venoms and we compare the S-S bonding patterns of proteins that are homologous to IX/X-bp.
凝血因子IX/因子X结合蛋白（IX/X-bp）是一种双链抗凝蛋白，从竹叶青蛇毒中分离得到。IX/X-bp的氨基酸序列与C型凝集素样蛋白的序列同源，如去唾液酸糖蛋白受体、四连蛋白和免疫球蛋白E的低亲和力Fcε受体。分析了由IX/X-bp的CNBr生成片段经酶切产生的含胱氨酸肽段的氨基酸组成和氨基酸序列，以确定该蛋白中七个二硫键的位置。A链中的三个二硫键将Cys2与Cys13、Cys30与Cys127、Cys102与Cys119相连。A链中的三个二硫键将Cys2与Cys13、Cys30与Cys119、Cys96与Cys111相连。链间二硫键将A链的Cys79和B链的Cys75相连。IX/X-bp的A链和B链的链内二硫键连接模式与其他C型凝集素样蛋白中的模式相似。在本报告中，我们讨论了IX/X-bp与从蛇毒中分离出的其他双链C型凝集素样蛋白之间的序列同源性，并比较了与IX/X-bp同源的蛋白质的S-S连接模式。
