ИСТИНА

Proteins have been the subject of intense interest from the very first steps of the electrochemistry and continue to be one of the favorite molecules of electrochemists until now. In 1980 two independent groups, of V. Bradec [1] and of J. A. Reynaud [2], demonstrated for the first time direct oxidation of proteins on solid electrodes as generated by their amino acid residues. At present there are lot of papers about amino acid redox activity on different electrode materials, however protein electrochemistry was not demonstrated in the majority of cases in the same conditions. Electrooxidation of proteins due to Tyr, Trp, Cys amino acid residues was shown on carbon screen printed electrodes (SPE). It is irreversible pH-dependent process. It was found based on 3D-models of protein molecules that protein electrochemical signal is proportional to the surface density of Tyr, Trp and Cys residues, but not to the amount of Tyr, Trp and Cys in the amino acid sequence. Also, it is possible to suggest that (i) proteins would not undergo denaturation in the course of electrochemical experiments at neutral pH and (ii) proper oriented surface amino acid residues take the major part in the protein oxidation signal. Linear calibration curves for amino acids and proteins were obtained in the different coordinates: of current-amino acid molar concentration and of current-logarithm of protein molar concentration. [3] The electrochemical activity of several commercially available and most-used proteins was examined on carbon SPE to find the quantitative relationships between electrochemical signal and protein structure for further biomedical application. The Alzheimer’s disease neuropeptide amyloid-beta contained one Tyr residue was used as a model for study of protein-metal ion complexing and protein aggregation. Therefore, the electrochemical method may serve as a simple, rapid, label-free approach for protein analysis, for the study of protein-protein and protein-ligand interactions as well as for registration of post-translational modification. Amino acid electrochemistry opens up new possibilities to biosensor constructions and to the monitoring of life processes. [1] V. Brabec, V. Mornstein, Electrochemical behaviour of proteins at graphite electrodes: I. Electrooxidation of proteins as a new probe of protein structure and reactions, Biochim. Biophys. Acta 625 (1980) 43. [2] J. A. Reynaud, B. Malfoy, A. Bere, The electrochemical oxidation of three proteins: RNAase A, bovine serum albumin and concanavalin A at solid electrodes, J. Electroanal. Chem. Interfacial Electrochem. 116 (1980) 595. [3] E. V. Suprun, M. S. Zharkova, G. E. Morozevich, A. V. Veselovsky, V. V. Shumyantseva, A. I. Archakov, Analysis of Redox Activity of Proteins on the Carbon Screen Printed Electrodes, Electroanalysis 25 (2013) 2109.