Theoretical Modeling Of The Orientations And Electron Transfer Of Cytochrome C On The Carbon Nanotubes’ Surface

Research on direct electrochemistry of redox proteins and enzymes provides the foundation for R&D of high-performance biosensor and biofuel cell catalyst,thus attracting wide attention.The cytoclhrome can be easily integrated on the biosensor and bio-electronic components thanks to its natural redox ability and small size.Therefore,it has been widely used as a research model in study of the absorbing process of redox proteins on electrode surfaces and electron transfer mechanismProperties of electrode surfaces(e.g.hydrophily,hydrophobicity,electropositivity,electronegativity,porosity,morphology,etc)influence locations,comformational changes and quantities of redox proteins on the surface.Locations,comformational changes and densities of redox proteins on electrode surfaces vary with the electrode materials.1D electrical conductivity,super large L/D ratio and strong biocompatibility make carbon nano tube an ideal electrode material for biocell.Firstly,we located the Cytc on different chiral single-wall carbon nano tubes(namely SWNT(10,10),SWNT(8,7),SWNT(7,6)and SWNT(6,5))with our own algorithm and four different primary localization methods to explore surface features of Cytc during simulation.The research showed that the Cytc maintained the secondary structures well,that is,the biological activity was good;tube diameter change did not influence protein localization much,but indirectly influenced overall localization features since carbon nano tube’s chirality is a key influencing factor for localization of protoheme embedded in proteins;and correct localization of Cytc on electrode surface played an important role in electron transfer efficiency between the electrodes and proteins.Then we simultaneously located three Cytc on four kinds of carbon nano tubes at the optimum location obtained from abovementioned study to explore aggregation behavior of multiple Cytc on carbon nano tube surface.The result showed that proteins did not aggregate and protoheme plane was always perpendicular to the tube surface when multiple Cytc were absorbed on the surface.At last,we simplified snapshot model of the stabilized best localization system SWNT(10,10)-Cytc,figured out its electron concentration by quantum mechanics simulation and discussed and verified pathway between the Cytc and carbon nano tube.The result showed that electrons went through a tunnel at Lys99 end of the Cytc to surface of the carbon nano tube and electron transfer pathway between the surface and Cytc was Fe-Met100-Lys99-SWNT.