Munkvad S, Jespersen J, Gram J, Overgaard K, Rånby M
Department of Clinical Chemistry, Ribe County Hospital, Esbjerg, Denmark.
Clin Chem. 1990 May;36(5):737-41.
We describe a rapid assay of C1-esterase inhibitor (C1-inh) activity in plasma. After adding purified C1s serine protease (EC 3.4.21.42) in excess to plasma, we determine the residual C1s activity towards a new chromogenic tripeptide, CH3CO-Lys(CbO)-Gly-Arg-pNA. Optimal conditions include the addition of methylamine (final concentration 0.12 mol/L) to reduce the potential inhibitory capacity of alpha 2-macroglobulin towards C1s and the addition of heparin (final concentration 3000 int. units/L) to enhance the reaction of C1s with C1-inh. The correlation with C1-inh antigen concentrations in plasma was excellent. The estimated interassay CV was 4.3%, whereas the intra-assay CV was 2.0% for activity concentrations within the range of normal individuals (means +/- 2 SD: 70-124%), 1.3% at lower concentrations. The method is more convenient, rapid, and precise than previous methods, and C1-inh activity in plasma can be assessed within 30 min. We found that concentrations of C1-inh in plasma were low during open-heart bypass surgery.
我们描述了一种血浆中C1酯酶抑制剂（C1-inh）活性的快速检测方法。向血浆中加入过量的纯化C1s丝氨酸蛋白酶（EC 3.4.21.42）后，我们测定其对一种新的发色三肽CH3CO-Lys（CbO）-Gly-Arg-pNA的残余C1s活性。最佳条件包括加入甲胺（终浓度0.12 mol/L）以降低α2巨球蛋白对C1s的潜在抑制能力，以及加入肝素（终浓度3000国际单位/L）以增强C1s与C1-inh的反应。与血浆中C1-inh抗原浓度的相关性极佳。对于正常个体范围内的活性浓度（均值±2 SD：70 - 124%），估计的批间变异系数为4.3%，而批内变异系数为2.0%，较低浓度时为1.3%。该方法比以前的方法更方便、快速且精确，血浆中的C1-inh活性可在30分钟内评估。我们发现心脏直视搭桥手术期间血浆中C1-inh的浓度较低。
