title: Entrapment of a water wire in a hydrophobic peptide channel with an aromatic lining.
abstract: A one-dimensional water wire has been characterized by X-ray diffraction in single crystals of the tripeptide Ac-Phe-Pro-Trp-OMe. Crystals in the hexagonal space group P6(5) reveal a central hydrophobic channel lined by aromatic residues which entraps an approximately linear array of hydrogen bonded water molecules. The absence of any significant van der Waals contact with the channel walls suggests that the dominant interaction between the "water wire" and "peptide nanotube" is electrostatic in origin. An energy difference of 16 kJ mol(-1) is estimated for the distinct orientations of the water wire dipole with respect to the macrodipole of the peptide nanotube. The structural model suggests that Grotthuss type proton conduction may, through constricted hydrophobic channels, be facilitated by concerted, rotational reorientation of water molecules.
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Upadhyayula Surya
authors.initials: US
authors.lastname: Raghavender
authors.forename: Bhaswati
authors.initials: B
authors.lastname: Chatterjee
authors.forename: Indranil
authors.initials: I
authors.lastname: Saha
authors.forename: Appavu
authors.initials: A
authors.lastname: Rajagopal
authors.forename: Narayanaswamy
authors.initials: N
authors.lastname: Shamala
authors.forename: Padmanabhan
authors.initials: P
authors.lastname: Balaram
mesh_terms: D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D055672:Static Electricity; D014867:Water / Q000737:chemistry*
chemical_list: D009842:Oligopeptides; D011522:Protons; D014867:Water