van Leeuwen B H, Millar J A, Hammat M T, Johnston C I
Clin Chim Acta. 1983 Feb 7;127(3):343-51. doi: 10.1016/0009-8981(83)90161-4.
Alcoholic extracts of blood collected for measurement of circulating bradykinin were analysed for co-extracted kininogen which would artificially elevate measured bradykinin levels. The blood extract contained a glycoprotein with identical chromatographic properties to kininogen. Bradykinin immunoreactivity in the extract eluted as a single peak from an immunoaffinity column of anti-bradykinin IgG bound to Sepharose identically to both bradykinin and kininogen showing immunoidentity of these substances. Affinity chromatography on Concanavalin A-Sepharose or ion-exchange chromatography on CM-Sephadex C25 separated bradykinin and the glycoprotein which again eluted identically to kininogen. The decrease in measured values of blood bradykinin after purification of the extract on CM-Sephadex C25 was a similar amount to that calculated as cross-reactivity with the amount of co-extracted kininogen. Hence radioimmunoassay of bradykinin in ethanolic extracts of blood is inaccurate owing to the presence of co-extracted kininogen, and additional purification steps such as chromatography on CM-Sephadex C25 are mandatory for accurate assay by ligand binding techniques.
为测量循环中的缓激肽而采集的血液酒精提取物，被分析其中共提取的激肽原，因为它会人为提高所测的缓激肽水平。血液提取物含有一种糖蛋白，其色谱特性与激肽原相同。提取物中的缓激肽免疫反应性从结合到琼脂糖凝胶上的抗缓激肽IgG免疫亲和柱上以单峰形式洗脱，与缓激肽和激肽原的洗脱情况完全相同，表明这些物质具有免疫同一性。在伴刀豆球蛋白A - 琼脂糖凝胶上进行亲和层析或在CM - 葡聚糖凝胶C25上进行离子交换层析，可分离缓激肽和该糖蛋白，其洗脱情况再次与激肽原相同。用CM - 葡聚糖凝胶C25对提取物进行纯化后，所测血液缓激肽值的下降幅度与根据与共提取激肽原的量的交叉反应计算出的下降幅度相似。因此，由于存在共提取的激肽原，血液乙醇提取物中缓激肽的放射免疫测定不准确，对于通过配体结合技术进行准确测定而言，诸如在CM - 葡聚糖凝胶C25上进行层析等额外的纯化步骤是必不可少的。
