Charge Transport Properties of Cytochrome b562 in Metal Junctions

G. N. Jonnalagadda, and Z. Futera

Faculty of science, University of South Bohemia, Branisovska 1760,

370 05, Ceske Budejovice, Czech Republic

Jonnag00@prf.jcu.cz

Life sustaining process, including respiration, photosynthesis, and various enzymatic catalytic activities, rely on electron transfer reactions mediated by redox proteins. One such protein, cytochrome b562 (cyt b562) found in Escherichia coli, contains a redox active heme (Fe2+/3+) cofactor bonded to the protein matrix, coordinated by axial histidine (His102) and methionine (Met7) ligands (Fig. 1.). The conductive properties of single cyt b562 adsorbed on gold surfaces were recently investigated using Electrochemical Scanning Tunneling Microscopy (EC-STM) [1], and we further examine the related adsorption structures by using computational techniques to elucidate the charge transport properties and mechanism.


We use classical molecular dynamics (MD) to study the structure and configuration of cytochrome b562 on gold surfaces, and a quantum mechanical approach based on Density Functional Theory (DFT) to investigate its electronic states at the protein/metal interfaces and junctions [2,3]. We simulate adsorption of mutated cyt b562 on the flat gold surface and use the obtained structures for the preparation of the cytochrome junction between gold contacts. We use the DFT+å approach to predict electronic state alignment, followed by interfacial coupling calculations using Project Operator-Biased Diabatization (POD) method to evaluate tunneling current with Landauer formalism [3,4]. Incoherent electronic flux through redox site was also computed and these findings have implications for the development of bioelectronic devices and materials.

A picture containing LEGO, toy Description automatically generated

Figure 1. Details of the redox-active heme site

Figure 2.  Mutated cyt b542 adsorbed onto a gold surface

 

1. M. Elliott, D.D. Jones, Biochem. Soc. Trans., 46, (2018), 9

2. O.V. Kontakanen, D. Biriukov, Z. Futera, J. Chem. Phys., 156, (2022), 175101

3. Z. Futera et all., J. Phys. Chem. Lett., 11, (2020), 9766

4. Z. Futera, X. Wu, J. Blumberger, J. Phys. Chem. Lett., 14, (2023), 445