Memon M S, Baskova I P
Biokhimiia. 1977 Mar;42(3):505-12.
Products of bovine prothrombin acylation by citraconic anhydride, modified to 20--90% have been obtained. Disc-electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate has shown that the citraconylation of prothrombin is accompanied with spontaneous activation, resulting in formation of products with molecular weights identical to those of neoprothrombin C, neoprothrombin T, profragment and fragments A and C. Spontaneous activation upon the citraconylation is never completely recovered: the reaction products always contain a fraction, corresponding in molecular weight to prothrombin. Citraconylation products possess neither coagulating, nor esterase activity. Generation of esterase activity requires the presence of an enzyme--factor Xa, which splits the 323-324 peptide bond (Arg-Ile) in the molecules of prothrombin and intermediate products of its activation. The mechanism of activation of citraconylated prothrombin products by factor Xa does not differ from the mechanism of native prothrombin activation by the enzyme. The esterase activity, which is generated after the incubation with factor Xa, is due to the building of citraconylthrombin and partly of the native thrombin; the latter may be formed at the low degree of prothrombin modification.
已获得经柠康酸酐酰化的牛凝血酶原产物，酰化程度为20%至90%。在十二烷基硫酸钠存在下于聚丙烯酰胺凝胶中进行圆盘电泳表明，凝血酶原的柠康酰化伴随着自发激活，导致形成分子量与新凝血酶原C、新凝血酶原T、前片段以及片段A和C相同的产物。柠康酰化时的自发激活从未完全恢复：反应产物总是含有一部分分子量与凝血酶原相对应的成分。柠康酰化产物既不具有凝血活性，也不具有酯酶活性。酯酶活性的产生需要酶——因子Xa的存在，因子Xa可裂解凝血酶原及其激活中间产物分子中的323 - 324肽键（精氨酸 - 异亮氨酸）。因子Xa对柠康酰化凝血酶原产物的激活机制与该酶对天然凝血酶原的激活机制并无不同。与因子Xa孵育后产生的酯酶活性归因于柠康酰凝血酶以及部分天然凝血酶的形成；后者可能在凝血酶原低程度修饰时形成。
