Kleniewski J, Blankenship D T, Cardin A D, Donaldson V
Department of Pediatrics, University of Cincinnati College of Medicine, OH.
J Lab Clin Med. 1992 Jul;120(1):129-39.
When purified high molecular weight kininogen was incubated with streptokinase-activated plasmin and kallikrein, a larger amount of kinin was released than would have been predicted from the effect of either enzyme alone. To determine the mechanism of this enhancement, high molecular weight kininogen was digested sequentially with these enzymes, and the rates of kinin release and sites of cleavage were determined. Conversion of 133 kd native high molecular weight kininogen to two-chain 112 kd or 102 kd derivatives by plasmin more than doubled the rate of kinin release by kallikrein. Conversely, digestion of high molecular weight kininogen by kallikrein and then plasmin did not enhance the rate of kinin release. The kallikrein cleavage points that provided 112 kd and 102 kd two-chain high molecular weight kininogen were after residues 437 (Arg-Lys) and 389 (Arg-Ser), whereas those for plasmin were after 438 (Lys-His) and 389 (Arg-Ser). epsilon-Aminocaproic acid, which competes for lysine residues that are critical to the binding of plasminogen or plasmin to substrates, inhibited the digestion of high molecular weight kininogen by plasmin, which is consistent with the evidence that the 438-439 Lys-His was a primary site of plasmin attack on high molecular weight kininogen. Furthermore, this cleavage was observed when plasminogen activation was induced in normal and in prekallikrein or Hageman factor-deficient plasmas. We suggest that the generation of fibrinolytic activity in blood could result in enhanced kinin release by kallikrein in regions of inflammation as a result of the collaborative actions of plasmin and kallikrein on high molecular weight kininogen.
当将纯化的高分子量激肽原与链激酶激活的纤溶酶和激肽释放酶一起孵育时，释放的激肽量比单独使用任何一种酶所预期的要多。为了确定这种增强作用的机制，用这些酶依次消化高分子量激肽原，并测定激肽释放速率和裂解位点。纤溶酶将133kd的天然高分子量激肽原转化为112kd或102kd的双链衍生物，使激肽释放酶释放激肽的速率增加了一倍多。相反，先用激肽释放酶然后用纤溶酶消化高分子量激肽原并没有提高激肽释放速率。产生112kd和102kd双链高分子量激肽原的激肽释放酶裂解位点在437位残基（精氨酸-赖氨酸）和389位残基（精氨酸-丝氨酸）之后，而纤溶酶的裂解位点在438位残基（赖氨酸-组氨酸）和389位残基（精氨酸-丝氨酸）之后。ε-氨基己酸可竞争对纤溶酶原或纤溶酶与底物结合至关重要的赖氨酸残基，它抑制了纤溶酶对高分子量激肽原的消化，这与438-439位赖氨酸-组氨酸是纤溶酶攻击高分子量激肽原的主要位点的证据一致。此外，在正常血浆以及前激肽释放酶或哈格曼因子缺乏的血浆中诱导纤溶酶原激活时，都观察到了这种裂解。我们认为，血液中纤溶活性的产生可能会由于纤溶酶和激肽释放酶对高分子量激肽原的协同作用，导致炎症区域中激肽释放酶释放激肽增加。
