title: Chirality-induced spin polarization places symmetry constraints on biomolecular interactions.
abstract: Noncovalent interactions between molecules are key for many biological processes. Necessarily, when molecules interact, the electronic charge in each of them is redistributed. Here, we show experimentally that, in chiral molecules, charge redistribution is accompanied by spin polarization. We describe how this spin polarization adds an enantioselective term to the forces, so that homochiral interaction energies differ from heterochiral ones. The spin polarization was measured by using a modified Hall effect device. An electric field that is applied along the molecules causes charge redistribution, and for chiral molecules, a Hall voltage is measured that indicates the spin polarization. Based on this observation, we conjecture that the spin polarization enforces symmetry constraints on the biorecognition process between two chiral molecules, and we describe how these constraints can lead to selectivity in the interaction between enantiomers based on their handedness. Model quantum chemistry calculations that rigorously enforce these constraints show that the interaction energy for methyl groups on homochiral molecules differs significantly from that found for heterochiral molecules at van der Waals contact and shorter (i.e., ∼0.5 kcal/mol at 0.26 nm).
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Anup
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Capua
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Kesharwani
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Jan M L
authors.initials: JM
authors.lastname: Martin
authors.affiliation: Evogene Ltd., Rehovot 76121, Israel.
authors.forename: Einat
authors.initials: E
authors.lastname: Sitbon
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: David H
authors.initials: DH
authors.lastname: Waldeck
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel; ron.naaman@weizmann.ac.il.
authors.forename: Ron
authors.initials: R
authors.lastname: Naaman
mesh_terms: D055664:Electrochemical Techniques; D005227:Fatty Acids / Q000737:chemistry*; D009842:Oligopeptides / Q000737:chemistry*; D011789:Quantum Theory; D013113:Spin Labels; D055672:Static Electricity; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: C505222:11-mercaptoundecanoic acid; D005227:Fatty Acids; D009842:Oligopeptides; D013113:Spin Labels; D013438:Sulfhydryl Compounds
keywords: biorecognition; chirality; enantioselectivity; exchange interaction; spin