title: Amphipathic solvation of indole: implications for the role of tryptophan in membrane proteins.
abstract: The microscopic structure of the tryptophan side chain, indole, in an amphiphilic environment has been investigated using a combination of neutron diffraction measurements and simulations in solution. The results show that indole is preferentially solvated by hydrogen bonding interactions between water and alcohol -OH groups rather than the interaction being dominated by indole-methyl interactions. This has implications for understanding how tryptophan interacts with the amphipathic membrane environment to anchor proteins into membranes, where the results here suggest that the benzene ring of tryptophan interacts directly with the interfacial water at the membrane surface rather than being buried into the hydrophobic regions of the membrane bilayer.
authors.affiliation: †Department of Biochemistry, University of Oxford, Oxford, U.K.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Johnston
authors.affiliation: ‡Department of Biochemistry, Princeton University, Princeton, New Jersey, United States.
authors.forename: Yapei Rosie
authors.initials: YR
authors.lastname: Zhang
authors.affiliation: ⊥German Engineering Materials Science Centre (GEMS), Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Geesthacht GmbH Lichtenbergstrasse 1, 85747 Garching bei München, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Busch
authors.affiliation: §Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Barcelona, Catalonia, Spain.
authors.forename: Luis Carlos
authors.initials: LC
authors.lastname: Pardo
authors.affiliation: ∥ISIS Facility, Rutherford Appleton Laboratory, Didcot, Chilton, U.K.
authors.forename: Silvia
authors.initials: S
authors.lastname: Imberti
authors.affiliation: †Department of Biochemistry, University of Oxford, Oxford, U.K.
authors.forename: Sylvia E
authors.initials: SE
authors.lastname: McLain
mesh_terms: D003198:Computer Simulation; D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007211:Indoles / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D008956:Models, Chemical; D033363:Neutron Diffraction; D010100:Oxygen / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D007211:Indoles; D008565:Membrane Proteins; D012997:Solvents; D014867:Water; D006859:Hydrogen; C030374:indole; D014364:Tryptophan; D010100:Oxygen; D000432:Methanol