Protein structural transition at negatively charged electrode surfaces. Effects of temperature and current density
Earlier it was shown that surface-attached bovine serum albumin undergoes ionic strength-induced structural transition at mercury electrodes. Using constant current chronopotentiometric stripping (CPS) here we show that this electric field-driven transition is influenced also by other factors, such as temperature, current density, and particularly by the time of surface-attached protein exposure to the negative potentials. For example, 1 s exposure to -1.6 V (against Ag/AgC1/3 M KC1) results in the protein denaturation. Exposures longer than 1 s resulted in protein denaturation even at less negative potentials. On the other hand, in CPS much shorter exposure times can be used. Exposing the surface-attached protein to negative potentials for ms time intervals the protein stability can be tested at different current densities. We investigated several proteins such as bovine and human serum albumins, ovalbumin, ot-macroglobulin and ot-synuclein, which showed various profiles in dependence on different parameters, including time of the protein exposure to negative potentials, ionic strengths and temperature. We believe that using this approach, new methods for testing surface-attached protein stabilities in relation to the electric field effects and to other factors can be developed. (C) 2015 Elsevier Ltd. All rights reserved.