Identification of a plasminogen binding region in streptokinase that is necessary for the creation of a functional streptokinase-plasminogen activator complex.
Identification of a plasminogen binding region in streptokinase that is necessary for the creation of a functional streptokinase-plasminogen activator complex.
复制标题
鉴定链激酶中的纤溶酶原结合区域，这对于创建功能性链激酶-纤溶酶原激活剂复合物是必需的。
DOI：
10.1021/bi00032a021
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Kussie,P
中科院分区：
文献类型：
--
作者：
Reed,GL;Lin,LF;Parhami-Seren,B;Kussie,P
修订稿于 7995 年 5 月 9 日收到®摘要：链激酶是一种纤溶酶原激活剂，广泛用于治疗心肌梗塞患者。然而，链激酶不是蛋白酶，必须首先与纤溶酶原结合并相互作用以形成酶复合物。通过测量重组链激酶片段与纤溶酶原的结合，我们首先试图鉴定链激酶中的纤溶酶原结合区域，其次探索结合（通过该区域）与功能性链激酶-纤溶酶原激活剂复合物的产生之间的关系。重组链激酶以可饱和且特异的方式与人谷氨酸纤溶酶原结合，解离常数为 4.2 x 10"10 M。跨越氨基酸 1-127 和 1-253 的重组链激酶片段不能与谷氨酸纤溶酶原结合，而跨越氨基酸 1-352、120-352 和 1-352 的片段不能与谷氨酸纤溶酶原结合。 244—414 紧密结合 纤溶酶原和每个片段完全抑制全长链激酶与纤溶酶原的结合。尽管这些链激酶片段与纤溶酶原形成复合物，但酶测定表明它们都不能产生活性位点。当这三个片段共享的链激酶区域（跨越残基 244-352）被表达时，它也结合纤溶酶原并竞争性抑制纤溶酶原。 通过全长链激酶形成功能性纤溶酶原激活剂复合物。总之，这些数据表明链激酶以高亲和力与纤溶酶原结合，纤溶酶原的主要结合区域位于氨基酸 244-352 内，并且通过该区域的结合对于生成功能性纤溶酶原激活剂复合物是必要的。纤溶酶原激活剂链激酶 (SK) 1 广泛用于 人类可以溶解引起心肌梗塞的血栓。 SK 是源自不同链球菌菌株的 414 个氨基酸的单链多肽（Malke 等，1985）。 SK 与人纤溶酶原激活剂尿激酶和组织纤溶酶原激活剂显着不同。这些人纤溶酶原激活剂是丝氨酸蛋白酶，可裂解肽键 纤溶酶原将其转化为活性酶纤溶酶。相反，SK 没有内在的酶活性。已经提出了几种理论来解释其作用机制（例如，Taylor & Beisswenger，1973；Kosow，1975；Jackson & Tang，1982；Nikandrov，1992），但大量数据支持 SK 功能的“激活剂复合物”模型[由
Revised Manuscript Received May 9, 7995® abstract: Streptokinase is a plasminogen activator widely usedto treat patients with myocardial infarction. However, streptokinase is not a protease, and must first bind and interact with plasminogen to form an enzymatic complex. By measuring the binding of recombinant streptokinase fragmentsto plasminogen, we have sought, first, to identify a plasminogen binding region in streptokinase and, second, to explore the relation between binding (via this region) and the generation of a functional streptokinase—plasminogen activator complex. Recombinant streptokinase bound in a saturable and specific manner to human Glu-plasminogen with a dissociation constant of 4.2 x 10 “10 M. Recombinant streptokinase fragments spanning amino acids 1-127 and 1-253 could not be shown to bind to Glu-plasminogen, whereas fragments spanning amino acids 1—352, 120—352, and 244—414 bound tightly to plasminogen and each fragment completely inhibited the binding of full-length streptokinase to plasminogen. Although these latter streptokinase fragments formed a complex with plasminogen, enzymatic assays indicated that none of them was capable of generating an active site. When the streptokinase region shared by these three fragments, spanning residues 244—352, was expressed, it also bound plasminogen and competitively inhibited the formation of a functional plasminogen activator complex by full-length streptokinase. Taken together, these data indicate that streptokinase binds to plasminogen with high affinity, that a primary binding region for plasminogen is located within amino acids 244—352, and that binding via this region is necessary for the generation of a functional plasminogen activator complex.The plasminogen activator streptokinase (SK) 1 is widely used in humans to dissolve the thrombi that cause myocardial infarctions. SK is a single-chain polypeptide of 414 amino acids derived from different strains of streptococcus (Malke et al., 1985). SK differs significantly from the human plasminogen activators urokinase and tissue plasminogen activator. These human plasminogen activators are serine proteases that cleave a peptide bond in plasminogen to convert it to the active enzyme plasmin. In contrast, SK has no intrinsic enzymatic activity. Several theories have been proposed to explain its mechanism of action (eg, Taylor & Beisswenger, 1973; Kosow, 1975; Jackson & Tang, 1982; Nikandrov, 1992), but the preponderance of data favors an “activator complex” model of SK function [reviewed by