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Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine.
Bioelectrochemistry. 2011 Apr; 81(1):46-52.B

Abstract

The electrochemical oxidation behaviour at boron doped diamond and glassy carbon electrodes of the sulphur-containing amino acids cysteine and methionine, using cyclic and differential pulse voltammetry over a wide pH range, was compared. The oxidation reactions of these amino acids are irreversible, diffusion-controlled pH dependent processes, and occur in a complex cascade mechanism. The amino acid cysteine undergoes similar three consecutive oxidation reactions at both electrodes. The first step involves the oxidation of the sulfhydryl group with radical formation, that undergoes nucleophilic attack by water to give an intermediate species that is oxidized in the second step to cysteic acid. The oxidation of the sulfhydryl group leads to a disulfide bridge between two similar cysteine moieties forming cysteine. The subsequent oxidation of cystine occurs at a higher potential, due to the strong disulfide bridge covalent bond. The electro-oxidation of methionine at a glassy carbon electrode occurs in two steps, corresponding to the formation of sulfoxide and sulfone, involving the adsorption and protonation/deprotonation of the thiol group, followed by electrochemical oxidation. Methionine undergoes a one-step oxidation reaction at boron doped diamond electrodes due to the negligible adsorption, and the oxidation also leads to the formation of methionine sulfone.

Authors+Show Affiliations

Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004–535 Coimbra, Portugal.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21377428

Citation

Enache, T A., and A M. Oliveira-Brett. "Boron Doped Diamond and Glassy Carbon Electrodes Comparative Study of the Oxidation Behaviour of Cysteine and Methionine." Bioelectrochemistry (Amsterdam, Netherlands), vol. 81, no. 1, 2011, pp. 46-52.
Enache TA, Oliveira-Brett AM. Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine. Bioelectrochemistry. 2011;81(1):46-52.
Enache, T. A., & Oliveira-Brett, A. M. (2011). Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine. Bioelectrochemistry (Amsterdam, Netherlands), 81(1), 46-52. https://doi.org/10.1016/j.bioelechem.2011.02.001
Enache TA, Oliveira-Brett AM. Boron Doped Diamond and Glassy Carbon Electrodes Comparative Study of the Oxidation Behaviour of Cysteine and Methionine. Bioelectrochemistry. 2011;81(1):46-52. PubMed PMID: 21377428.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine. AU - Enache,T A, AU - Oliveira-Brett,A M, Y1 - 2011/02/24/ PY - 2010/10/19/received PY - 2011/01/18/revised PY - 2011/02/07/accepted PY - 2011/3/8/entrez PY - 2011/3/8/pubmed PY - 2011/8/10/medline SP - 46 EP - 52 JF - Bioelectrochemistry (Amsterdam, Netherlands) JO - Bioelectrochemistry VL - 81 IS - 1 N2 - The electrochemical oxidation behaviour at boron doped diamond and glassy carbon electrodes of the sulphur-containing amino acids cysteine and methionine, using cyclic and differential pulse voltammetry over a wide pH range, was compared. The oxidation reactions of these amino acids are irreversible, diffusion-controlled pH dependent processes, and occur in a complex cascade mechanism. The amino acid cysteine undergoes similar three consecutive oxidation reactions at both electrodes. The first step involves the oxidation of the sulfhydryl group with radical formation, that undergoes nucleophilic attack by water to give an intermediate species that is oxidized in the second step to cysteic acid. The oxidation of the sulfhydryl group leads to a disulfide bridge between two similar cysteine moieties forming cysteine. The subsequent oxidation of cystine occurs at a higher potential, due to the strong disulfide bridge covalent bond. The electro-oxidation of methionine at a glassy carbon electrode occurs in two steps, corresponding to the formation of sulfoxide and sulfone, involving the adsorption and protonation/deprotonation of the thiol group, followed by electrochemical oxidation. Methionine undergoes a one-step oxidation reaction at boron doped diamond electrodes due to the negligible adsorption, and the oxidation also leads to the formation of methionine sulfone. SN - 1878-562X UR - https://www.unboundmedicine.com/medline/citation/21377428/Boron_doped_diamond_and_glassy_carbon_electrodes_comparative_study_of_the_oxidation_behaviour_of_cysteine_and_methionine_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1567-5394(11)00007-7 DB - PRIME DP - Unbound Medicine ER -