L-Cysteine electrooxidation in alkaline and acidic... - BV FAPESP
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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

L-Cysteine electrooxidation in alkaline and acidic media: a combined spectroelectrochemical and computational study

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Author(s):
Dourado, Andre H. B. ; de Lima Batista, Ana P. ; Oliveira-Filho, Antonio G. S. ; Sumodjo, Paulo T. A. ; Cordoba de Torresi, Susana I.
Total Authors: 5
Document type: Journal article
Source: RSC ADVANCES; v. 7, n. 13, p. 7492-7501, 2017.
Web of Science Citations: 9
Abstract

Due to the numerous possible oxidation states of sulfur, L-cysteine and L-cystine are very important amino acids that are utilized to understand the adsorption and redox activity of proteins and peptides. Therefore, the study of the adsorption/oxidation of these molecules can be used as a model system to understand protein behaviour. The aim of the present communication is to study this adsorption/oxidation process by infrared spectroscopy and DFT/PBE-D3/def2-SVP/COSMO (water) calculations. A bridge geometry (S bonded to two Pt atoms) was found to be the chemical adsorption link formed, and experimental data corroborate the DFT predictions. For both species, the surface-carboxyl group interaction is stronger at lower pH values, and the conformations of the adsorbed species were found to be dependent on the pH, with the amino group getting closer to the surface along with increases in the electrolyte alkalinity. The oxidation study was also performed at different pH values, and a Kolbe decarboxylation was found to be a side reaction at every pH, being more important in strong acidic solutions. Sulfur-containing adsorbed oxidized species were inferred based on the optimized structures of the adsorbed/desorbed species. A complex oxidation mechanism is proposed here, and species, such as sulfoxide, adsorbed sulfoxide, sulfenic and sulfinic acids and adsorbed sulfone, are suggested as intermediates in the oxidation of L-cysteine to sulfonic acid. (AU)

FAPESP's process: 15/22203-6 - N-Heterocyclic Carbene Based Compounds in CO2 Activation: A Computational Approach
Grantee:Ana Paula de Lima Batista
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 13/25592-8 - Study of L-cysteine and L-cystine adsorption on platinum electrodes
Grantee:André Henrique Baraldi Dourado
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
FAPESP's process: 15/11714-0 - Reactivity, transformation, fixation, and spectroscopy of systems involving CO2
Grantee:Antonio Gustavo Sampaio de Oliveira Filho
Support Opportunities: Regular Research Grants