钒酸根、金属离子和腺苷二磷酸的相互作用-ATP及Mg^2^+-ATP类似物的形成

用钒-51核磁共振方法研究钒酸根在不同浓度和离子强度下, 在生理pH水溶液中的物种分配。研究结果表明毫摩尔级浓度的钒酸根主要以中心钒原子为四面体构型的单体、二聚、四聚和五聚体存在。通过比较所得的平衡常数说明在离子强度降低时, 钒酸根的聚合度下降。对于钒酸根-ADP体系, 从所显示的核磁谱变化通过计算得到相应的结合平衡常数, 说明主要发生的反应一是形成ATP类似物ADPV(V代表四面体构型的单体钒酸根); 二是在ADP浓度相对高时, 钒酸根与ADP核糖基上2', 3'-颗位羟基同时作用形成2:2配比的、钒原子为五配位三角双锥构型的配合物。在钒酸根-ADP体系中加入Mn^2^+后, ^5^1V NMR的变化说明ATP的类似物ADPV中β-磷酸根和γ-钒酸根可以协同螯合Mn^2^+, 表明形成了Mg^2^+-ATP的类似物Mn^2^+-ADPV。

The binding of vanadate and divalent metal ion to ADP-the formation of ATP and Mg^2^+-ATP analogues

The formation of ATP analogue, ADPV and the binding of paramagnetic Mn^2^+ to ADPV were studied in detail by ^5^1V NMR method in aqueous solution and the pH close to physiological condition. The polymerization of vanadate was found to decrease with decreasing ionic strength. The results show that the reactions occur between monomeric or dimeric vanadate and ADP in two different ways leading to the formation of an ATP analogue-ADPV with vanadate in the tetrahedral monomeric form and at higher concentration of ADP, a binuclear vanadate complex, in which vanadate bind simultaneously with the 2' and 3'-hydroxyl groups of the ribose ring. Their equilibrium constants of formation reactions were obtained. The ^5^1V NMR spectra changes significantly on the addition of paramagnetic Mn^2^+ into aqueous solution of vanadate and ADP. Based on the spectra it was indicated that the β-phosphate and γ-vanadate of ADPV chelate Mn^2^+ simultaneously with the formation of a Mg^2^+-ATP analogue, Mn^2^+- ADPV.