Redox chemistry of carbon-centered α-amino acid radicals†

Abstract

In this work we present the one-electron oxidation potentials of the α-amino carbon-centered radicals of glutathione, glutathione diethylester hydrochloride, cysteine ethylester hydrochloride and cystine dimethylester dihydrochloride in aqueous solution and N-dimethylglycine ethylester, N-Boc-proline, N-Boc-leucine and N-Boc-glycine in acetonitrile measured by photomodulation voltammetry. The potentials were found to be –0.30, –0.27, –0.06, 0.05, –0.23, –0.40, –0.48 and –0.38 V vs. NHE, respectively, under the present experimental conditions. On the basis of these results and previously published results, the nature of α-amino acid and peptide radicals, glutathione in particular, is discussed.