MECHANISM OF IRON REMOVAL FROM TRANSFERRIN

血清转铁蛋白是一种负责转运 同化、利用和储存部位之间的铁。这个 低分子量络合剂的作用机理 从这种蛋白质中去除铁离子仍然不是很清楚。 对除铁过程的表征是基本的 对于理解细胞内铁的释放和 铁处理用新型络合剂的研究进展 慢性输血疗法导致的超负荷 与贫血有关，如地中海贫血。 已经提出了相互冲突的机制来解释 儿茶酚、磷酸盐、 磷酸盐类和羟甲酸类配体。在最初的时期 在这个项目中，它表明它的两个机制都不是 最简单的形式是正确的，并提出了一个修正的速率定律 它包括两条平行的除铁路径。这个 拟议研究的目的是勾勒出 与每条路径相关联的步骤。这些研究还将 确定两种转铁蛋白之间的动力学差异 结合部位。 用可见光跟踪铁离子的除铁动力学 分光光度测定法。快速扫描分光光度法将是 用于跟踪铁离子对载脂蛋白的捐赠和 碳酸氢盐与三元转铁蛋白络合物的反应 含有膦酸协同离子。分子间相互作用的动力学研究 将包括从转铁蛋白中去除三价A1和In， 利用295 nm处的紫外光波段跟踪反应。这些金属 离子分别比铁离子更惰性和更不稳定， 因此，人们应该观察到以下步骤的反应速率的变化 包括打破铁配体的键。 化学修饰电极循环伏安法的出现 区分铁转铁蛋白的两种不同形式 减少率。这项技术将用于直接监测 转铁蛋白的构象随pH的变化， 温度和添加的盐。高附加值的盐。高场31p 核磁共振将被用来表征相互作用 含脱铁蛋白和二铁转铁蛋白的磷酸盐。这个 目的是鉴定所谓的混合配基中间体 参与了这些配体的除铁，表征了配体 结合位置，并估计其与铁离子的距离。

Serum transferrin is the protein responsible for the transport of iron between sites of assimilation, utilization, and storage. The mechanism by which low molecular weight chelating agents remove ferric ion from this protein is still not clearly understood. Characterization of the iron removal process is of fundamental important for understanding intracellular iron release and for the development of new chelating agents for the treatment of iron overload that results from the chronic transfusion therapy associated with anemias such as -thalassemia. Conflicting mechanisms have been proposed to explain the saturation kinetics observed with catecholate, phosphate, phosphonate, and hydroxamate ligands. During the initial period of this project, it was shown that neither mechanism in its simplest form is correct, and a modified rate law was proposed which includes two parallel pathways for iron removal. The purpose of the proposed research is to delineate the mechanistic steps associated with each pathway. These studies will also determine the kinetic differences between the two transferrin binding sites. Iron removal kinetics for ferric ion will be followed using visible spectrophotometry. Rapid scanning spectrophotometry will be used to follow the donation of ferric ion to apotransferrin and the reactions of bicarbonate with ternary transferrin complexes containing a phosphonate synergistic ion. Kinetic studies on the removal of trivalent A1 and In from transferrin will be included, using the uv band at 295 nm to follow the reaction. These metal ions are respectively more inert and more labile than ferric ion, and thus one should observe shifts in reaction rates for steps that involve breaking of iron-ligand bonds. Cyclic voltammetry with chemically modified electrodes appears to distinguish two forms of ferric transferrin which differ in their rate of reduction. This technique will be used to directly monitor conformation changes of ferric transferrin as a function of pH, temperature, and added salts. High added salts. High field 31p nmr will be used to characterize the interactions of the phosphonates with both apo- and diferric transferrin. The objective is to identify the purported mixed-ligand intermediates involved in iron removal by these ligands, characterize the ligand binding site, and estimate its distance from the ferric ion.