Hoem N O, Johannesen S, Briseid K
Department of Pharmacology, University of Oslo, Norway.
Thromb Res. 1989 May 1;54(3):197-205. doi: 10.1016/0049-3848(89)90227-2.
Factor XII was assayed in acetone-treated and kaolin-activated human citrated plasma (total plasma dilution 1.0 + 0.3 v/v during activation with kaolin, 1.8 mg/ml incubate). Measurements were performed with the tetrapeptide Bz-Ile-Glu-Gly-Arg-pNa (S-2222) and with prekallikrein as substrates. The correlation of both methods to another S-2222 based method recently described was good, r = 0.90 and 0.85 for the two methods respectively. Under the assay conditions used, FXIIa was present as a S-2222 amidase that could be blocked by corn inhibitor, whereas plasma kallikrein was found to be present partly as an amidase blocked by a low concentration of soybean trypsin inhibitor, and partly in a functional state not inhibited and adding to the measured level of FXII. The presence of benzamidine 0.7 to 2.1 mM during acetone treatment increased the measured level of FXII assayed both as prekallikrein activator and as S-2222 amidase.
在丙酮处理并经高岭土激活的人枸橼酸盐血浆中检测因子 XII（在用高岭土激活期间血浆总稀释度为 1.0 + 0.3 v/v，孵育浓度为 1.8 mg/ml）。使用四肽 Bz-Ile-Glu-Gly-Arg-pNa（S-2222）和前激肽释放酶作为底物进行测量。这两种方法与最近描述的另一种基于 S-2222 的方法的相关性良好，两种方法的 r 值分别为 0.90 和 0.85。在所使用的检测条件下，FXIIa 以一种可被玉米抑制剂阻断的 S-2222 酰胺酶形式存在，而血浆激肽释放酶部分以被低浓度大豆胰蛋白酶抑制剂阻断的酰胺酶形式存在，部分以未被抑制的功能状态存在，并增加了所测得的 FXII 水平。在丙酮处理期间存在 0.7 至 2.1 mM 的苯甲脒会增加作为前激肽释放酶激活剂和 S-2222 酰胺酶检测的 FXII 的测量水平。
