Mechanism of Indium(III) Exchange between NTA and Transferrin: A Kinetic Approach
作者:Tarita Biver、Rossella Friani、Chiara Gattai、Fernando Secco、Maria Rosaria Tiné、Marcella Venturini
DOI:10.1021/jp8045033
日期:2008.9.25
intermediate MLTB which then evolves to an "open" MTB* ternary complex complex with expulsion of L. In turn, this complex interconverts to a "closed", more stable, form MTB. Neither the prevailing complex M2L nor the TB2 form of transferrin are directly involved in the exchange process but act as metal and protein reservoirs. The pH dependence of the reaction has been also investigated. The slow phase has not
在含碳酸氢钠的水溶液中研究了次氮基三乙酸(NTA)与牛血清转铁蛋白(T)之间In(3+)交换过程的平衡和动力学。已经通过差示紫外光谱法在25℃,pH = 7.4和I = 0.2M(NaClO 4)下测量了金属交换平衡。还测量了NTA的酸解离常数和In(III)与NTA的结合常数。动力学实验表明,运铁蛋白从[In(NTA)2](3-)吸收In(3+)的过程是双相的,快相在几秒钟内完成,慢相持续数小时。快速相已通过停止流方法进行了研究,并产生了单指数动力学。它涉及1:1复杂ML(M = In,L = NTA)与TB(T =转铁蛋白,B = CO 3(2-))得到四级中间体MLTB,其随后随着排出L而演变成“开放的” MTB *三元复合物。反过来,该复合物相互转化成“封闭的”,更稳定的MTB形式。流行的复杂的M2L和TB2形式的转铁蛋白都没有直接参与交换过程,而是充当了金属和蛋白质的储存库。还研