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Title: Infrared spectral marker bands characterizing a transient water wire inside a hydrophobic membrane protein

Proton conduction along protein-bound “water wires” is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations. A non-hydrogen bonded (“dangling”) O–H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Department of Biophysics, Ruhr-University Bochum, Universitätsstraße 150, 44780 Bochum (Germany)
  2. (China)
  3. Department of Biophysics, Chinese Academy of Sciences, Max-Planck-Gesellschaft Partner Institute for Computational Biology, 320 Yue Yang Road, 200031 Shanghai (China)
  4. Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
22413315
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHEMICAL PROPERTIES; FOURIER TRANSFORMATION; GROUND STATES; MEMBRANE PROTEINS; MOLECULES; PROTONS; QUANTUM MECHANICS; SIMULATION; SPECTROSCOPY; TRANSIENTS; WATER