Gustafson E J, Schutsky D, Knight L C, Schmaier A H
J Clin Invest. 1986 Jul;78(1):310-8. doi: 10.1172/JCI112567.
Studies were performed to determine if the unstimulated platelet membrane has a site for high molecular weight kininogen (HMWK) binding. 125I-HMWK bound to unstimulated platelets. Zn++ was required for 125I-HMWK binding to unstimulated platelets and binding was maximal at 50 microM Zn++. Neither Mg++ nor Ca++ substituted for Zn++ in supporting 125I-HMWK binding to unstimulated platelets, and neither ion potentiated binding in the presence of 50 microM zinc. 125I-HMWK competed with equal affinity with HMWK for binding, and excess HMWK inhibited 125I-HMWK-platelet binding. Only HMWK, not prekallikrein, Factor XII, Factor XI, Factor V, fibrinogen, or fibronectin inhibited 125I-HMWK-platelet binding. 125I-HMWK binding to unstimulated platelets was 89% reversible within 10 min with a 50-fold molar excess of HMWK. Unstimulated platelets contained a single set of saturable, high affinity binding sites for 125I-HMWK with an apparent dissociation constant of 0.99 nM +/- 0.35 and 3,313 molecules/platelet +/- 843. These studies indicate that the unstimulated external platelet membrane has a binding site for HMWK that could serve as a surface to modulate contact phase activation.
进行了多项研究以确定未受刺激的血小板膜是否具有高分子量激肽原（HMWK）结合位点。125I-HMWK可与未受刺激的血小板结合。125I-HMWK与未受刺激的血小板结合需要Zn++，且在50 microM Zn++时结合量最大。在支持125I-HMWK与未受刺激的血小板结合方面，Mg++和Ca++均不能替代Zn++，且在存在50 microM锌的情况下，这两种离子均不能增强结合。125I-HMWK与HMWK以相同亲和力竞争结合，过量的HMWK可抑制125I-HMWK与血小板的结合。只有HMWK，而非前激肽释放酶、因子XII、因子XI、因子V、纤维蛋白原或纤连蛋白可抑制125I-HMWK与血小板的结合。在10分钟内，用50倍摩尔过量的HMWK可使125I-HMWK与未受刺激血小板的结合89%可逆。未受刺激的血小板含有一组单一的、可饱和的、对125I-HMWK具有高亲和力的结合位点，其表观解离常数为0.99 nM±0.35，每个血小板有3313个分子±843个。这些研究表明，未受刺激的血小板外部膜具有HMWK结合位点，该位点可作为调节接触相激活的表面。
