Subramanian K M, Wolf W
Radiopharmacy Program, University of Southern California, Los Angeles.
J Nucl Med. 1990 Apr;31(4):480-8.
A new method was developed to determine the stability constants of bifunctional chelates of indium (In) coupled to a protein. This method utilizes the displacement reaction between an indium complex and ferric ion. By measuring the position equilibrium constant 'K' of this reaction and knowing the stability constant of the corresponding ferric chelate, the overall formation constant of the indium chelate can be determined. Human serum albumin (HSA) was conjugated with ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) using their cyclic dianhydrides. A new method was developed to couple triethylenetetraminehexaacetic acid (TTHA) with HSA using Woodward's Reagent K. The chelating agents coupled to HSA were complexed with indium-114m-(114mIn) labeled indium and purified by dialysis or microcentrifugation. The stability constants of these indium complexes were determined at physiologic pH using ferric chelate of nitrilotriacetic acid (Fe-NTA) as the source of ferric ion. No significant differences were found between the stability constants of the indium chelates conjugated to protein and those of unconjugated species.
开发了一种新方法来测定与蛋白质偶联的铟（In）双功能螯合物的稳定常数。该方法利用铟络合物与铁离子之间的置换反应。通过测量该反应的位置平衡常数“K”并知道相应铁螯合物的稳定常数，就可以确定铟螯合物的总形成常数。人血清白蛋白（HSA）使用其环状二酐与乙二胺四乙酸（EDTA）和二乙烯三胺五乙酸（DTPA）共轭。开发了一种使用伍德沃德试剂K将三亚乙基四胺六乙酸（TTHA）与HSA偶联的新方法。与HSA偶联的螯合剂与铟-114m-（114mIn）标记的铟络合，并通过透析或微量离心进行纯化。使用次氮基三乙酸铁螯合物（Fe-NTA）作为铁离子源，在生理pH下测定这些铟络合物的稳定常数。发现与蛋白质共轭的铟螯合物的稳定常数与未共轭物种的稳定常数之间没有显著差异。
