Modeling of the Electrostatic Interaction of [NiFe] Hydrogenases on a Planar Electrode скачать в хорошем качестве

Modeling of the Electrostatic Interaction of [NiFe] Hydrogenases on a Planar Electrode

Modeling of the Electrostatic Interaction and Catalytic Activity of [NiFe] Hydrogenases on a Planar Electrode (final presentation) Abstract Hydrogenases are a group of enzymes that can catalyze the redox reaction of hydrogen. 2H+ + 2e- H2 Hydrogenases can be used for the generation of molecular hydrogen or electricity, avoiding the use of rare materials like platinum in electrolyzers and fuel cells. The incorporation of hydrogenases in electrochemical devices requires a good orientation that facilitates the transfer of electrons from the surface of the electrode to the catalytic center of the enzyme through the array of the iron-sulfur clusters that are part of these enzymes. This study presents a computational approach to study the relevance of the orientations of the experimental variables of pH, ionic strength, and electric potential. The obtained results indicate that an electric potential of ±0.05 V does not have a significant effect on the orientations of the [NiFe] hydrogenase on the electrode, while the ionic strength reduces the interaction energy and, for that reason, the adsorption of the enzyme. The pH rises as the most important factor determining the orientation of the adsorption of the hydrogenase on the electrode. To evaluate if an orientation is favorable to catalyze the redox reaction of hydrogen, the combination of two characteristics was considered: the probability and the current produced for such orientation. This combination reveals that there are no dominant orientations that determine the transfer of electrons. The current generation results from a contribution of all the orientations under determinate certain conditions. As a final step, the effect of protein concentration (or its equivalent, the osmotic pressure) on the total current was considered. The solution with pH=5 seems to be marginally better due to the combination of a slightly high current density and slightly better overall absorption. The overall protein absorption and preferential orientations may be improved further by functionalization of the electrode or modification of the protein, to incorporate some amino acids at selected points on its surface. This study demonstrates that electrostatic interactions between hydrogenase and an electrode are affected by pH, ionic strength, and the orientation of the protein. link to article https://pubs.acs.org/doi/10.1021/acs.... link to thesis https://www.politesi.polimi.it/handle...