The Electrochemical Behavior of α-Ketoglutarate at the Hanging Mercury Drop Electrode in Acidic Aqueous Solution and Its Practical Application in Environmental and Biological Samples

• Published in: Electroanalysis (New York, N.Y.) N.Y.), 2004-06, Vol.16 (12), p.1051-1058
• Main Authors: Yang, Li, Yang, Zhengbiao, Zhang, Min, Ni, Haiyan, Ji, Ming, Tang, Yongzheng, Yang, Xiaodi, Long, Xiufen, Bi, Shuping
• Format: Article
• Language: English
• Subjects: Aluminum; Differential pulse polarography; Electrochemical behaviors; Glutamate dehydrogenase (GDH) reaction system; Glutamic acid; Inhibitory and activation of enzyme; Linear scan voltammetry; NAD; NADH; α-Ketoglutarate
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.200302913

The voltammetric behavior of α‐ketoglutarate (α‐KG) at the hanging mercury drop electrode (HMDE) has been investigated in acetate buffer solution. Under the optimum experimental conditions (pH 4.5, 0.2 M NaAc‐HAc buffer solution), a sensitive reductive wave of α‐KG was obtained by linear scan voltammetry (LSV) and the peak potential was −1.18 V (vs. SCE), which was an irreversible adsorption wave. The kinetic parameters of the electrode process were α=0.3 and ks=0.72 1/s. There was a linear relationship between peak current ip, α‐KG and α‐KG concentration in the range of 2×10−6–8×10−4 M α‐KG. The detection limit was 8×10−7 M and the relative standard deviation was 2.0% (Cα‐KG=8×10−4 M, n=10). Applications of the reductive wave of α‐KG for practical analysis were addressed as follows: (1) It can be used for the quantitative analysis of α‐KG in biological samples and the results agree well with those obtained from the established ultraviolet spectrophotometric method. (2) Utilizing the complexing effect between α‐KG and aluminum, a linear relationship holds between the decrease of peak current of α‐KG Δip and the added Al concentration C Al III in the range of 5.0×10−6–2.5×10−4 M. The detection limit was 2.2×10−6 M and the relative standard deviation was 3.1% (C Al III=4×10−5 M, n=10). It was successfully applied to the detection of aluminum in water and synthetic biological samples with satisfactory results, which were consistent with those of ICP‐AES. (3) It was also applied to study the effect of AlIII on the glutamate dehydrogenase (GDH) activity in the catalytically reaction of α‐KG+NH$\rm{ {_{4}^{+}}}$+NADH⇌L‐glutamate+NAD++H2O by differential pulse polarography (DPP) technique. By monitoring DPP reductive currents of NAD+ and α‐KG, an elementary important result was found that Al could greatly affect the activity of GDH. This study could be attributed to intrinsic understanding of the aluminum's toxicity in enzyme reaction processes.