Electroanalytical exploitation of quinone-thiol interactions: application to the selective determination of cysteine

Square wave voltammetry was applied to the detection of cysteine through the use of an indirect assay that exploits the reaction of the thiol with a quinone indicator. Voltammetric discrimination between unreacted quinone and the corresponding quinone-cysteine adduct is possible with clear resolutio...

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Bibliographic Details
Published in:Analyst (London) 2001-01, Vol.126 (3), p.353-357
Main Authors: HIGNETT, Geraldine, THRELFELL, Sarah, WAIN, Andrew J, LAWRENCE, Nathan S, WILKINS, Shelley J, DAVIS, James, COMPTON, Richard G, CARDOSI, Marco F
Format: Article
Language:English
Subjects:
Aminoacids, peptides. Hormones. Neuropeptides
Analytical chemistry
Analytical, structural and metabolic biochemistry
Benzoquinones - chemistry
Biological and medical sciences
Chemistry
Cysteine - urine
Electrochemical methods
Electrochemistry
Exact sciences and technology
Fundamental and applied biological sciences. Psychology
Humans
Proteins
Sensitivity and Specificity
Sulfhydryl Compounds - chemistry
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Summary:Square wave voltammetry was applied to the detection of cysteine through the use of an indirect assay that exploits the reaction of the thiol with a quinone indicator. Voltammetric discrimination between unreacted quinone and the corresponding quinone-cysteine adduct is possible with clear resolution of the latter peak providing a linear response from 5 to 47 microM. The selectivity of the approach was assessed with no interference from cystine, lysine, paracetamol or 4-aminophenol. The response recorded in the presence of a massive excess of ascorbic acid was also investigated and the integrity of the approach confirmed. The effects of other sulfhydryl thiols, homocysteine and glutathione, were also assessed and found to present no appreciable change in the voltammetric profile. The practical utility of the approach was investigated through examining the response to cysteine in urine.
ISSN:0003-2654
1364-5528
DOI:10.1039/b008616i