Messori L, Orioli P, Banholzer V, Pais I, Zatta P
Department of Chemistry, University of Florence, Italy.
FEBS Lett. 1999 Jan 15;442(2-3):157-61. doi: 10.1016/s0014-5793(98)01651-2.
The reaction of human serum apotransferrin with titanium(IV) citrate under physiological conditions results in the formation of a specific bis-titanium(IV) transferrin adduct (Ti2Tf hereafter) with two titanium(IV) ions loaded at the iron binding sites. The same specific Ti2Tf complex is formed by reacting apotransferrin with titanium(III) chloride and exposing the sample to air. The derivative thus obtained was characterized by spectroscopic techniques, including absorption, UV difference, circular dichroism and 13C NMR spectroscopies, and shown to be stable within the pH range 5.5-9.0. Surprisingly, the reaction of apoTf with titanium(IV) nitrilotriacetate (NTA) does not lead to formation of appreciable amounts of Ti2Tf, even after long incubation times, although some weak interactions of Ti(IV)-NTA with apoTf are spectroscopically detected. Implications of the present results for a role of transferrin in the uptake, transport and delivery of soluble titanium(IV) compounds under physiological conditions are discussed.
在生理条件下，人血清脱铁转铁蛋白与柠檬酸钛（IV）反应会形成一种特定的双钛（IV）转铁蛋白加合物（以下简称Ti2Tf），在铁结合位点负载有两个钛（IV）离子。通过使脱铁转铁蛋白与氯化钛（III）反应并将样品暴露于空气中，也会形成相同的特定Ti2Tf复合物。由此获得的衍生物通过光谱技术进行了表征，包括吸收光谱、紫外差光谱、圆二色光谱和13C NMR光谱，并显示在pH值5.5 - 9.0范围内稳定。令人惊讶的是，脱铁转铁蛋白与次氮基三乙酸钛（IV）（NTA）的反应即使经过长时间孵育也不会导致形成可观量的Ti2Tf，尽管通过光谱检测到Ti（IV）-NTA与脱铁转铁蛋白之间存在一些弱相互作用。本文讨论了这些结果对转铁蛋白在生理条件下对可溶性钛（IV）化合物的摄取、运输和递送中所起作用的影响。
