Istituto CNR di Chimica Biomolecolare, Trav. La Crucca 3, I-07040 Sassari, Italy.
Inorg Chem. 2009 Jul 6;48(13):5747-57. doi: 10.1021/ic802287s.
The complexation of the VO(2+) ion in several systems that can model the physiological conditions of its transport in blood serum was studied using electron paramagnetic resonance (EPR) spectroscopy. Particularly, the ternary systems formed by (i) VO(2+) and two high-molecular-mass components of blood serum, human serum apo-transferrin (hTf) and human serum albumin (HSA); (ii) VO(2+), hTf, and bL; and (iii) VO(2+), HSA, and bL, where bL is one of the six most important low-molecular-mass bioligands of the blood serum (bL = lactate, citrate, oxalate, phosphate, glycine, or histidine), were examined. The results indicate that, in aqueous solution, transferrin is a stronger binder than albumin, and at the physiological ratio, most of the VO(2+) ion is present as (VO)(2)hTf, and a small amount as (VO)(2)(d)HSA, the dinuclear species formed by albumin where the two metal ions are interacting and the spin state S is 1. Among the bL ligands, only lactate and citrate are able to bind VO(2+) in the presence of transferrin or albumin, the others not interacting at all. Finally, the quaternary systems formed by (i) VO(2+), hTf, HSA, and lactate and (ii) VO(2+), hTf, HSA, and citrate were studied. In these cases, the results suggest that the predominant species is (VO)(2)hTf, followed by the mixed complexes VO(2+)-hTf-lactate or VO(2+)-hTf-citrate, whereas (VO)(2)(d)HSA and (VO)(2)(citrH(-1))(2) are minor components at physiological pH. The conclusions of this study give new insights on how the VO(2+) ion distributes among the blood serum components and is transported in the plasma toward the target sites in the organism.
使用电子顺磁共振（EPR）光谱研究了 VO(2+)离子在几种可以模拟其在血清中运输的生理条件的体系中的络合作用。特别是研究了由（i）VO(2+)和血液血清中的两种高分子质量成分，人血清脱铁转铁蛋白（hTf）和人血清白蛋白（HSA）；（ii）VO(2+)、hTf 和 bL；以及（iii）VO(2+)、HSA 和 bL 形成的三元体系，其中 bL 是血液血清中六种最重要的低分子质量生物配体之一（bL = 乳酸盐、柠檬酸盐、草酸盐、磷酸盐、甘氨酸或组氨酸）。结果表明，在水溶液中，转铁蛋白是比白蛋白更强的配体，在生理比例下，大部分 VO(2+)离子以（VO）（2)hTf 的形式存在，少量以（VO）（2)(d)HSA 的形式存在，这是白蛋白形成的双核物种，其中两个金属离子相互作用，自旋态 S 为 1。在 bL 配体中，只有乳酸盐和柠檬酸盐能够在转铁蛋白或白蛋白存在的情况下与 VO(2+)结合，其他配体根本不相互作用。最后，研究了由（i）VO(2+)、hTf、HSA 和乳酸盐和（ii）VO(2+)、hTf、HSA 和柠檬酸盐形成的四元体系。在这些情况下，结果表明主要物种是（VO）（2)hTf，其次是混合络合物 VO(2+)-hTf-乳酸盐或 VO(2+)-hTf-柠檬酸盐，而（VO）（2)(d)HSA 和 (VO)(2)(citrH(-1))(2) 是生理 pH 值下的次要成分。这项研究的结论提供了关于 VO(2+)离子如何在血清成分之间分配以及在血浆中向生物体中的靶部位运输的新见解。
