- Electrochemical Determination of Salivary N-Acetylneuraminic Acid by Miniaturized Capillary Electrophoresis Coupled with Sample Stacking
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Due to their important biological role as markers for different pathologies, sialic acid (SA) analyses are important for clinical research. In this work, a miniaturized capillary electrophoresis with amperometric detection (mini-CE-AD) was developed for the determination of N-acetylneuraminic acid (NANA), which is the most widespread form of SAs. NANA was first oxidized by periodic acid in an acidic solution, and then the oxidation product β-formyl pyruvic acid was derivatized with electroactive 2-thiobarbituric acid (TBA) to form an electroactive NANA-TBA adduct, which could be readily determined by mini-CE-AD. The limit of detection (LOD) of NANA-TBA could achieve 0.50 μg/mL (1.6 μmol·L?1, S/N=3) based on an online enrichment approach of moving chemical reaction boundary. The proposed method was successfully applied to the analysis of NANA in human saliva, and the recoveries were in the range of 91.8% –109% with RSDs of 1.8% –3.9%. Due to its simple design and construction, low cost and portability, the mini-CE-AD device will possess more practicability in more field work as an alternative to conventional and microchip CE approaches.
- Zheng, Yiliang,Wang, Tingting,Kong, Jiaxing,Ma, Yaolu,Heng, Yi,Ren, Yujuan,Ye, Jiannong,Chu, Qingcui
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- Investigating the role of the hydroxyl groups of substrate erythrose 4-phosphate in the reaction catalysed by the first enzyme of the shikimate pathway
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3-Deoxy-d-arabino-heptulosonate 7-phosphate (DAH7P) synthase catalyses the first step of the shikimate pathway, which is responsible for the biosynthesis of aromatic amino acids in microorganisms and plants. This enzyme catalyses an aldol reaction between phosphoenolpyruvate and d-erythrose 4-phosphate to generate DAH7P. Both 2-deoxyerythrose 4-phosphate and 3-deoxyerythrose 4-phosphate were synthesised and tested as alternative substrates for the enzyme. Both compounds were found to be substrates for the DAH7P synthases from Escherichia coli, Pyrococcus furiosus and Mycobacterium tuberculosis, consistent with an acyclic mechanism for the enzyme for which neither C2 nor C3 hydroxyl groups are required for catalysis. The enzymes all showed greater tolerance for the loss of the C2 hydroxyl group than the C3 hydroxyl group.
- Tran, David,Pietersma, Amy L.,Schofield, Linley R.,Rost, Matthias,Jameson, Geoffrey B.,Parker, Emily J.
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supporting information; experimental part
p. 6838 - 6841
(2012/01/03)
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