Rosenthal H E, Albert M, Ludwig G, Strumlauf E, Sandberg A A
J Steroid Biochem. 1982 May;16(5):639-41. doi: 10.1016/0022-4731(82)90100-5.
The results of determination of plasma transcortin levels by gel filtration are subject to assay conditions such as duration of incubation and the amount of cortisol added. We investigated the cause for the dependency of results on assay conditions by incubating samples over prolonged periods of time. Transcortin concentration and the rate of dissociation of the cortisol-transcortin complex remained constant over many weeks of storage at 4 degree C, while irreversible binding to unidentified macromolecules increased continuously. Irreversible binding occurs faster at 37 degrees C than at 4 degrees C. In addition, with time, an ether-extractable, less polar metabolite of cortisol appears in the serum. The data suggest that a highly reactive metabolite of cortisol enters into covalent binding with macromolecules during prolonged incubations.
通过凝胶过滤法测定血浆皮质素结合球蛋白水平的结果会受到诸如孵育时间和添加皮质醇量等测定条件的影响。我们通过长时间孵育样品来研究结果对测定条件产生依赖性的原因。在4℃下储存数周期间，皮质素结合球蛋白浓度以及皮质醇 - 皮质素结合物的解离速率保持恒定，而与未鉴定大分子的不可逆结合则持续增加。不可逆结合在37℃时比在4℃时发生得更快。此外，随着时间的推移，血清中会出现一种可被乙醚提取的、极性较小的皮质醇代谢产物。数据表明，在长时间孵育过程中，一种高反应性的皮质醇代谢产物与大分子发生了共价结合。
