Molecular basis for the fibrinogen structure and functions-Analysis Of hereditary dysfibrinogens and their application to the study

1. 通过透射电子显微镜（TEM），我们研究了由于氨基酸取代而产生的Asn- x -Thr/Ser型序列与Asn残基连接的额外糖分子的作用。在纤维蛋白原Asahi中，由于γ γ- 310与Thr取代而与γAsn-308残基连接的额外糖分子被认为干扰了E-D结合和纤维蛋白γ链的交联。事实上，去除糖的运动导致形成了有序的纤维蛋白网络，并具有适当的分支，尽管由于点突变，D: D关联仍然存在。因此，我们得出结论，额外的糖部分在很大程度上负责这种异常纤维蛋白原的功能异常。相反，纤维蛋白原Lima中高比例的二二化低聚糖（78%）由于唾液酸而产生电斥力，并扰乱了纤维蛋白原原纤维在聚合物上的横向结合。生化研究表明，单独去除唾液酸可以形成正常的纤维蛋白超结构。一种独特的异常纤维蛋白原，纤维蛋白原大阪VI与12残基延伸的bb链。在一名曾两次分娩严重出血的36岁女性的异常纤维蛋白原中，我们发现了b β链的12个残基延伸，这是由于Lys从（TAG）停止到（AAG）的转变。这样，又翻译了36个碱基对。有趣的是，在新c端第二个位置的两个相应的Cys残基之间形成了一个或两个二硫桥，导致末端连接的纤维蛋白原同型二聚体的形成，如TEM所示，它们平行或串联排列。这些纤维蛋白原二聚体包含在原纤维中似乎与高度分支和脆弱的纤维蛋白凝块的形成有关。研究结果发表在《血液》96(12):3779-3785,2000年，同时也发表在《纽约科学院年鉴》上。少

1. The Molecular Mechanisms of Extra Asn-linked OligosaccharidesBy transmission electron microscopy (TEM), we have studied the role of extra sugar moiteis linked to Asn residues due to creation of an Asn-X-Thr/Ser type sequence owing to an amino acid substitutionIn fibrinogen Asahi, the extra sugar moities linked to γAsn-308 residues due to a γMet-310 to Thr substitution are suggested to interfere with the E-D binding and cross-linking of the fibrin γ-chain. Indeed, removal of the sugar moities resulted in the formation of well ordered fibrin networks with appropriate branching, although the D : D association still remained owing to the point mutation. Thus, we conclude that the extra sugar moieties are largely responsible for the functional abnormality in this dysfibrinogen.On the contrary, a high proportion of disialylated oligosaccharide in fibrinogen Lima (78%) generates electric repulsive forces due to sialic acids and disturbs lateral association of fibrin protofibrils on polymer … More ization. Removal of sialic acids alone lead to formation normal fibrin ultra structures as has been suggested by biochemical studies.2. Characterization of a unique dysfibrinogen, fibrinogen Osaka VI with a 12 residue extension of the Bb-chain.In a dysfibrinogen derived from a 36-year-old woman who had suffered from severe bleeding on two occasions of childbirth, we have identified a 12-residue extension of the Bβ-chain due to a transition of (TAG) for stop to (AAG) for Lys. Thus, additional 36 base pairs are translated. Interestingly, one or two disulfide bridges are formed between two corresponding Cys residues at the second position from the new C-terminus, leading to formation of end-linked fibrinogen homodimers, which are aligned either in parallel or in tandem as demonstrated by TEM.Inclusion of these fibrinogen dimers in protofibrils seems to be related to the formation of highly branched and fragile fibrin clots.The results have been reported in Blood 96(12) : 3779-3785, 2000 and also in the Annals of New York Academy of Sciences, in press. Less