Abstract
Recent progress in label-free electrochemical analysis of biomacromolecules, such as proteins, nucleic acids and carbohydrates is reviewed. Since the 1970s electrochemical analysis of proteins focused on non-protein redox-active components of a relatively small group of conjugated proteins. In the recent decade, the ability of practically of all proteins to catalyze hydrogen evolution at mercury-containing electrodes was utilized for development of the protein structure-sensitive analysis. Some amino acid residues, such as arginine, lysine and cysteine contribute to the catalytic hydrogen evolution reaction (CHER) at neutral pH yielding protein reduction signals at highly negative potentials. It was found that native proteins do not lose their folded structure when adsorbed at mercury electrode close to the potential of zero charge. Surface-attached proteins get however denatured due to the electric field effects during their prolonged exposure to negative potentials. Using the constant current chronopotentiometric stripping it was possible to limit the exposure time to milliseconds preventing protein denaturation. The method was utilized in detection of changes in protein structures due to mutation, chemical modification, aggregation, damage by environmental agents, as well as to studies of poorly soluble membrane proteins, DNA–protein and protein–protein interactions, etc. Application of voltammetric methods, such as fast scan CV and normal pulse voltammetry showed smaller sensitivity to tiny changes in protein structures. Recently CHER was found also in some polysaccharides such as chitosan and in NH2 group-containing glycans. Very recent development in electrochemical analysis of DNA and RNA was briefly summarized.
Published Version
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