Petersen L C, Jørgensen M
Biochem J. 1983 Apr 1;211(1):91-7. doi: 10.1042/bj2110091.
Binding of heparin to thrombin is monitored by means of an aqueous two-phase partition system, and binding of heparin to antithrombin is monitored by means of heparin induced enhancement of the intrinsic fluorescence of the protein. Both types of binding are studied at various electrolyte compositions of the medium. Heparin is displaced from thrombin at lower concentrations of electrolyte than those necessary for its displacement from antithrombin. K+ is more efficient than Na+, which is again more efficient than Li+ in displacing heparin from these proteins. The kinetics of the reaction between thrombin and antithrombin in the presence of heparin were studied by using an assay where synthetic peptide substrate is present in the reaction mixture during the reaction between proteinase and inhibitor. The kinetics are studied at various electrolyte compositions of the medium and the results are compared with those obtained from the binding studies performed under similar conditions. The results are consistent with a model where binding of heparin to antithrombin causes enhancement of the reaction rate, and where this enhancement is abolished again when additional binding of heparin to thrombin takes place on further addition of heparin.
通过水相两相分配系统监测肝素与凝血酶的结合，通过肝素诱导的蛋白质固有荧光增强来监测肝素与抗凝血酶的结合。在介质的各种电解质组成条件下研究了这两种结合类型。与将肝素从抗凝血酶上置换下来所需的电解质浓度相比，在较低浓度的电解质条件下，肝素就能从凝血酶上被置换下来。在从这些蛋白质上置换肝素方面，K+比Na+更有效，而Na+又比Li+更有效。在蛋白酶和抑制剂反应期间，反应混合物中存在合成肽底物，通过这种测定方法研究了肝素存在下凝血酶与抗凝血酶之间反应的动力学。在介质的各种电解质组成条件下研究了动力学，并将结果与在类似条件下进行的结合研究所得结果进行比较。结果与这样一个模型一致，即肝素与抗凝血酶的结合会导致反应速率提高，而当进一步添加肝素导致肝素与凝血酶发生额外结合时，这种提高又会被消除。
