Studies on the physiological function of sugar chains and the activation mechanism of human von Willebrand factor

1.新的von--bitiscetin的氨基酸全序列。测定了双斑蛇蛇毒中的Willebrand因子(VWF)调节蛋白。Bitiscetin是由α和β亚基的二硫键连接的杂二聚体组成的。这两个亚基都显示了一个C型凝集素基序，并且与另一个调节子Botrocetin只有45%的相似性。竞争研究表明，Bitiscetin与vWF A1结构域中的一个位点结合，该位点与Botrocetin结合位点关系密切。监测接受ABO血型不合骨髓移植患者血浆vWF的ABO血型抗原表达。红细胞上的血型抗原逐渐转变为供者的血型，但vWF上的抗原即使在几年后仍保持原始受者的血型。在ABO血型不合的外周血和脐带血干细胞移植的情况下也得到了同样的结果。从眼镜蛇(Naja Kaouthia Cobra)蛇毒中分离纯化出一种新的vWF结合和裂解金属蛋白酶Kaouthiagin。Kaouthiagin特异性地切割Pro-708和Asp-709之间的vWF，以减少vWF的多聚体结构，导致失去由瑞斯托星诱导的血小板聚集性和vWF.4的胶原结合活性。从布鲁霍夫曲霉蛇毒中分离纯化了一种新的血小板GPIB结合蛋白--乳粘菌素，并克隆了该蛋白的全长基因。从蛇毒中分离纯化出一种新的纤维蛋白原裂解丝氨酸蛋白酶，并测定了该酶的氨基酸序列。Halystase还裂解血浆激肽原产生缓激肽，导致大鼠低血压。

1. The complete amino acid sequence of bitiscetin, a novel von. Willebrand factor (vWF) modulator protein from Bitis arietans snake venom, was determined. Bitiscetin was composed of disulfidelinked heterodimer of alpha and beta subunits. Both the subunits showed a C-type lectin motif and only 45% similarity to another modulator, botrocetin. The competition study suggests that bitiscetin binds to a site in the A1 domain of vWF located closely to the botrocetin-binding site.2. ABO blood group antigen expression on plasma vWF of the patients who received ABO-mismatched bone marrow transplantation was monitored. Blood group antigens on the red blood cells gradually turned to the donor's type, but the antigens on the vWF still maintained the original recipient's type even after several years. The same results were obtained in the case of ABO-mismatched peripheral blood and cord blood stem cell transplantation.3. A novel vWF-binding and -cleaving metalloproteinase named kaouthiagin was purified from Naja kaouthia cobra venom. Kaouthiagin specifically cleaved vWF between Pro-708 and Asp-709 to diminish the multimeric structure of vWF, resulting in the loss of ristocetin-induced platelet aggregability and collagen-binding activity of vWF.4. A novel platelet GPIb-binding protein named mamushigin was purified from A.blomhoffii snake venom and the cDNA of mamushigin was cloned.5. A novel fibrinogen-cleaving serine protease named halystase was purified from the snake venom of Agkistrodon halys blomhoffii and the complete amino acid sequence of halystase was determined. Halystase also cleaved plasma kininogen to produce bradykinin, causing the hypotension in rat.