Analytical Sciences

Abstract − Analytical Sciences, 19(2), 273 (2003).

Multimethod Characterization of the Interaction of Aluminum Ion with alpha-Ketoglutaric Acid in Acidic Aqueous Solutions
Xiaodi YANG, Shuping BI,  Xianlong WANG, Jian LIU, and Zhiping BAI
State Key Laboratory of Coordination Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, P. R. China
It has recently been reported that aluminum plays a very important role in reducing the activity of Krebs-cycle enzymes and glutamate dehydrogenase in rat brain homogenate. Therefore, it is necessary to identify the aluminum binding ability with the pivotal substrate alpha-ketoglutarate in biological systems. The interactions of aluminum with alpha-ketoglutarate were studied with pH-potentiometry, cyclic voltammetry, UV-vis, 1H, 27Al-NMR and Raman spectra multi-analytical techniques in acidic aqueous solution to measure the stoichiometries and stability constants of the complexes and its keto-enol tautomerism. The alpha-ketoglutarate was found to bind Al in a bidentate manner at the carboxylate and carbonyl moieties. The mononuclear 1:1 (AlLH-1, AlL+, AlHL2+) and 2:1 (AlL2-, AlL2H-23-) species, and dinuclear 2:1 (Al2L4+) species were found in acidic aqueous solution. Meanwhile, Al can promote alpha-KG tautomerize to its enolic-structure compounds in solutions. These findings may help to further understand the influence of Al on GDH enzyme reactions in biological systems.