Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode

• Authors: Ryszard Drożdż , Jerzy Naskalski , Anna Ząbek-Adamska
• Languages of publication: EN

Abstracts

EN

A potentiometric procedure for cysteine thiol group concentration monitoring in media generating free radicals was developed using a thiol specific silver-mercury electrode. Electrolytic deposition of mercury on a silver wire and treatment with 20 mM cysteine in 0.5 M NaOH were used to produce the electrode. A silver-chloride electrode in saturated KCl was the reference. A glass capillary with 1 M KNO3 in 1% agarose gel was the liquid junction. The electrode responded to cysteine concentration in the range from 0.01 to 20 mM yielding a perfect linear relationship for the dependence of log [cysteine] versus electrode potential [mV], with b0 (constant) = -373.43 [mV], b1 (slope) = -53.82 and correlation coefficient r2 = 0.97. The electrode potential change per decade of cysteine concentration was 57 mV. The minimal measurable signal response was at a cysteine concentration of 0.01 mM. The signal CV amounted to 4-6% for cysteine concentrations of 0.01 to 0.05 mM and to less than 1% for cysteine concentrations of 0.5 to 20 mM. The response time ranged from about 100 s for cysteine concentrations of 0.01 to 0.1 mM to 30 s at higher cysteine concentrations. The standard curve reproducibility was the best at cysteine concentrations from 0.1 to 20 mM. In a reaction medium containing cysteine and copper(II)-histidine complex ([His-Cu]2+) solution in 55 mM phosphate buffer pH 7.4 the electrode adequately responded to changes in cysteine concentration. Beside cysteine, the silver-mercury electrode responded also to thiol groups of homocysteine and glutathione, however, the Nernst equation slope was about half of that for cysteine.

Keywords

EN

potentiometry; cysteine; real time assay; homocysteine; glutathione

• Publisher: Polish Biochemical Society
• Journal: Acta Biochimica Polonica
• Year: 2007
• Volume: 54
• Issue: 1
• Pages: 205-211

Dates

published

2007

revised

2006-02-02

received

2006-11-06

accepted

2007-02-16

(unknown)

2007-03-09

Contributors

author

Ryszard Drożdż

• Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland

author

Jerzy Naskalski

• Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland

author

Anna Ząbek-Adamska

• Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland

References

• Calvo-Marzal P, Chumbimuni-Torres KY, Hoehr NF, Kubota LT (2006) Determination of glutathione in hemolysed erythrocyte with amperometric sensor based on TTF-TCNQ. Clin Chim Acta 371: 152-158.
• Heyrovsky M, Mader P, Vavricka S, Vesela V, Fedurco M (1997) The anodic reactions at mercury electrode due to cysteine. J Electroanal Chem 430: 103-117.
• Hidayat A, Hibbert DB, Alexander PW (1997) Amperometric detection of organic thiols at a tungsten wire electrode following their separation by liquid chromatography. J Chromatogr B Biomed Sci Appl 693: 139-146.
• Jin W, Wang J (1997) Determination of cysteine by capillary zone electrophoresis with end-column amperometric detection at a gold/mercury amalgam microelectrode without deoxygenation. J Chromatogr A 769: 307-314.
• Kachur AV, Koch CJ, Biaglow JE (1999) Mechanism of copper-catalyzed autoxidation of cysteine. Free Radic Res 31: 23-34.
• Kolar M, Dobcnik D (2003) Chemically prepared silver electrode for determination of N-acetyl-l-cysteine by flow-injection potentiometry. Pharmazie 58: 25-28.
• Kolar M, Dobcnik D, Radic N (2000) Potentiometric flow injection determination of vitamin C and glutathione with a chemically prepared silver tubular electrode. Pharmazie 55: 913-917.
• Kolar M, Dobcnik D, Radic N (2002) Chemically treated silver electrodes for determination of cysteine. Microchem Acta 138: 23-27.
• Lawrence NS, Davis J, Compton RG (2001) Electrochemical detection of thiols in biological media. Talanta 53: 1089-1094.
• Ozoemena K, Westbroek P, Nyokong T (2001) Long-term stability of a gold electrode modified with a self assambled monolayer of octabutylthiophtalocyaninato-cobalt(II) towards l-cysteine detection. J Electrochem Commun 3: 529-534.
• Sugawara K, Hoshi S, Akatsuka K, Shimazu K (1996) Electrochemical behaviour of cysteine at a NafionR/cobalt(II) modified electrode. J Electroanal Chem 414: 253-256.
• Yang W, Gooding JJ, Hibbert BB (2001) Characterization of gold electrodes modified with self-assambled monolayers of l-cysteine for the adsorptive stripping analysis of copper. J Electroanal Chem 516: 10-16.
• Yosypchuk B, Novotny L (2002) Cathodic stripping voltametry of cysteine using silver and copper solid amalgam electrodes. Talanta 56: 971-976.
• Zhao C, Zhang J, Song J (2001) Determination of l-cysteine in amino-acid mixture and human urine by flow-injection analysis with a biamperometric detector. Anal Biochem 297: 170-176.