Entrapment of a Water Wire in a Hydrophobic Peptide Channel with an Aromatic Lining

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• 作者：Upadhyayula Surya Raghavender ; Bhaswati Chatterjee ; Indranil Saha ; Appavu Rajagopal ; Narayanaswamy Shamala ; Padmanabhan Balaram
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：July 28, 2011
• 年：2011
• 卷：115
• 期：29
• 页码：9236-9243
• 全文大小：1039K
• 年卷期：v.115,no.29(July 28, 2011)
• ISSN：1520-5207

文摘

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 P6₅ 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 鈥渨ater wire鈥?and 鈥減eptide nanotube鈥?is electrostatic in origin. An energy difference of 16 kJmol^鈥? 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.