Voltammetric and chronopotentiometric protein structure-sensitive analysis

Abstract

Previously we showed that constant current chronopotentiometric stripping (CPS) is convenient for protein analysis based on the ability of some amino acid residues to catalyze hydrogen evolution on mercury-containing electrodes. This method showed a remarkable sensitivity to changes in protein structures, including protein denaturation and even small protein damage. Here we used normal pulse voltammetric stripping (NPVS) with bare and dithiothreitol-modified hanging mercury drop electrode. We found that NPV pulses denatured the surface-attached protein but we showed conditions under which this method was able to distinguish native and denatured proteins with sensitivity approaching that of CPS. Using NPVS it was possible to follow bovine serum albumin (BSA) thermal denaturation as well as to investigate the effect of NPV pulses on the structure of the surface-attached protein. In addition to BSA we studied several proteins, such as human serum albumin, ovalbumin, urease, aldolase, concanavalin A, histone and vasopressin peptide. Our results suggest that CPS remains the method-of-choice for studies of changes in protein structure and of biochemical processes, such as DNA-protein specific binding, lectin-glycoprotein interactions, detection of protein damage, etc., while voltammetric methods, such as NPVS may suit better for investigation of the processes which proteins undergo at the electrode surface.