Tankersley D L, Alving B M, Finlayson J S
Blood. 1983 Aug;62(2):448-56.
A system was developed for studying the activation of factor XII (Hageman factor) in the presence of dextran sulfate (DS). Salient features of the system included low ionic strength (0.08), low concentration of factor XII (approximately 1/10,000 that in normal plasma), and an excess of exogenous prekallikrein (PK). In this system, factor XII was rapidly converted to the 80,000 molecular weight (mol wt) form of factor XIIa (alpha-factor-XIIa). Once formed, the factor XIIa converted PK to kallikrein at a rate that was proportional to the amount of factor XII originally present in the incubation mixture. This system was used to construct a simple sensitive assay for factor XII in plasma and other biologic samples. The kallikrein produced was measured spectrophotometrically with the chromogenic substrate (H-D-Pro-Phe-Arg-p-nitroanilide (S-2302). This assay was shown to be independent of the high molecular weight kininogen and the PK content of the sample being analyzed. The measurements obtained were consistent with fundamental enzymologic principles and, if desired, could be processed with a simple calculator program to achieve linear standard curves. When applied to the quantitation of factor XII in plasma, the assay yielded values in close agreement with those determined by coagulant assay or by radial immunodiffusion.
开发了一种用于研究在硫酸葡聚糖（DS）存在下因子 XII（哈格曼因子）激活的系统。该系统的显著特点包括低离子强度（0.08）、低因子 XII 浓度（约为正常血浆中浓度的 1/10,000）以及过量的外源性前激肽释放酶（PK）。在该系统中，因子 XII 迅速转化为分子量 80,000 的因子 XIIa 形式（α-因子 XIIa）。一旦形成，因子 XIIa 以与孵育混合物中最初存在的因子 XII 量成比例的速率将 PK 转化为激肽释放酶。该系统用于构建一种简单灵敏的血浆和其他生物样品中因子 XII 的检测方法。用发色底物（H-D-脯氨酸-苯丙氨酸-精氨酸-对硝基苯胺（S-2302））通过分光光度法测定产生的激肽释放酶。该检测方法被证明与高分子量激肽原和被分析样品的 PK 含量无关。获得的测量结果符合基本的酶学原理，并且如果需要，可以用简单的计算器程序进行处理以获得线性标准曲线。当应用于血浆中因子 XII 的定量时，该检测方法得到的值与通过凝血检测或放射免疫扩散测定的值非常一致。
