Chirality-Induced Spin Selectivity in Biology:The Role of Spin-Polarized Electron Current in Biological Electron Transport & Redox Enzymatic Activity

Arizona State University, Scottsdale AZ

Investigators

Abstract

Charge transport is a fundamental process in biological systems, it underlies cell activity and metabolism. The research involved in this project aims to expand our understanding about how electrons, the charge carriers, travel long distances in biological materials that are very poor conductors, as opposed to home or industrial electrical wires. It also focuses on a specific kind of enzymatic process where enzymes accelerate the chemical reactions involved in processes where biomolecules are oxidized or reduced, that is lose or gain electrons, a fundamental step in cell functionality. In this project, electron transport in biomolecules is studied through a synergistic theory-experimental effort which relies on advanced peptide synthesis and protein engineering and the measurement of currents at the single-molecule level. This research is relevant for our understanding of biological and cell function. Also, it advances our knowledge regarding fundamental aspects of electron transport in right-handed and left-handed molecules, which are pervasive in biological system. The investigation can also be of importance in the areas of sensing and molecular quantum information. A postdoctoral fellow will be receive cross-training by interactions with international collaborators. This project will create a link between academia and industry by delivering fundamental knowledge for sensor and diagnostic platforms. This project will study the role the electron spin-polarization generated in a chiral peptide matrix has on two remarkably efficient redox-based processes in biology; (1) the long-range electron transport and (2) the redox enzymatic reactions, both mediated by redox cofactors. These two aims will be achieved by first investigating the spin-polarization mechanisms of the electric current flowing through bespoke helical peptides, which constitute the main building blocks of the chiral matrix surrounding redox cofactors. Second, evaluating the impact of the above helix-induced spin-polarization in the electron transport efficiency of a model redox cytochrome. And third, evaluating its impact in the reaction rate of a redox enzymatic processes. The study will be carried out at the single peptide/protein level of resolution using a unique approach that combines advanced single-molecule conductance characterization with peptide synthesis and protein engineering. The single-peptide/protein method to measure molecular conductance is carried out in a precisely controlled nanoscale electrode-electrode gap of an electrochemical scanning tunnelling microscope, which allows operation in physiological conditions. This biophysical approach integrates an atomistic computational modelling of electron conductance of the entire single-molecule device, including both the molecules and the contacts. This collaborative US/UK project is supported by the US National Science Foundation and the UK Biotechnology and Biological Sciences Research Council where NSF funds the US investigator and BBSRC funds the UK partner. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.