Electrocatalytic Assay for Monitoring Methylglyoxal-Mediated Protein Glycation

Abstract

Protein glycation is a complex process that plays an important role in diabetes mellitus, aging, and the regulation of protein function in general. As a result, current methodological research on proteins is focused on the development of novel approaches for investigating glycation and the possibility of monitoring its modulation and selective inhibition. In this paper, a first sensing strategy for protein glycation is proposed, based on protein electroactivity measurement. Concretely, the label-free method proposed is based on the application of a constant-current chronopotentiometric stripping (CPS) analysis at Hg-containing electrodes. The glycation process was monitored as the decrease in the electrocatalytic protein signal, peak H, observed at highly negative potentials at around -1.8 V (vs Ag/AgCl3 M KCl), which was previously ascribed to a catalytic hydrogen evolution reaction (CHER). Using this method, a model protein bovine serum albumin was investigated over 3 days of incubation with the glycation agent methylglyoxal in the absence or presence of the glycation inhibitor aminoguanidine (pimagedine). The electrochemical methodology presented here could open up new possibilities in research on protein glycation and oxidative modification. The methodology developed also provides a new option for the analysis of protein intermolecular interactions using electrochemical sensors, which was demonstrated by the application of a silver solid amalgam electrode (AgSAE) for monitoring the glycation process in samples of bovine serum albumin, human serum albumin, and lysozyme.

Redox properties and human serum albumin binding of nitro-oleic acid

“…This procedure can be applied for evaluating HSA binding capacity, as was recently reported in Refs. [52,53]. In contrast, the cathodic peak of the binding ligand NO 2 -OA is not observable at low concentrations (Fig.…”

Electrochemistry of Nonconjugated Proteins and Glycoproteins. Toward Sensors for Biomedicine and Glycomics

“…These advantages are gradually finding ground in biomedicine. Very recently it has been shown 899 that glycation (section 9.5.1 ) of BSA results in a decrease or disappearance of electrocatalytic peak H (section 5 ). Moreover, we show that EC analysis can be applied also in glycomics to analyze glycans directly in glycoproteins on the cell surface or after their isolation.…”

Protein structural transition at negatively charged electrode surfaces. Effects of temperature and current density

“…By means of peak H, nanomolar concentrations of practically any protein can be analyzed at low current densities [6]. This peak showed its usefulness also in the analysis of membrane proteins [9] and protein glycation [10]. At high current densities peak H is sensitive to changes in protein structures [6,11], capable to recognize a single aa exchange in mutants as compared to parent wild type proteins [12].…”