scholarly journals 1P248 One-way proton transport in bacteriorhodopsin is modulated by changes in the interaction of the Schiff base with water molecules

2004 ◽  
Vol 44 (supplement) ◽  
pp. S91
Author(s):  
A. Maeda ◽  
Robert B. Gennis ◽  
Sersei P. Balashov ◽  
Thomas G. Ebrey
Keyword(s):  
Schiff Base ◽  
Proton Transport ◽  
Water Molecules

Water Molecules in the Schiff Base Region of Bacteriorhodopsin

2003 ◽  
Vol 125 (44) ◽  
pp. 13312-13313 ◽  
Author(s):  
Mikihiro Shibata ◽  
Taro Tanimoto ◽  
Hideki Kandori
Keyword(s):  
Schiff Base ◽  
Water Molecules ◽  
Base Region

Membranes Assembled from Narrow Carbon Nanotubes Block Proton Transport and Can Form Effective Nano-Filtration Devices

2006 ◽  
Vol 3 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Anton Burykin ◽  
Arieh Warshel
Keyword(s):  
Carbon Nanotubes ◽  
Proton Transport ◽  
Computational Study ◽  
Water Channel ◽  
Water Transfer ◽  
Water Molecules ◽  
Nano Technology ◽  
Nano Filtration ◽  
Double Wall ◽  
Aquaporin Water Channel

The use of carbon nanotubes in various filtration devices is a promising current direction in nano-technology. The direction of progress is, however, far from obvious when it involves devices that can allow water to be transferred while blocking proton transport. This problem is addressed in the present paper by exploiting the perspective that emerge from our recent studies of the mechanism of proton blockage in aquaporins. The paper focuses on a computational study of the free energy barriers for transfer of proton and water molecules through the membrane assembled from the double wall (5;5)@(10;10) armchair carbon nanotubes. It shows that such system can be used as a water nano filter that allows water transfer while blocking protons. Thus such carbon nanotube membrane will work as an artificial analog of aquaporin water channel. The general mechanisms of proton transfer/blockage in biological and artificial nanosystems are also discussed.

Aqua{5,5′-dihydroxy-2,2′-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato-κ4 O,N,N′,O′}zinc(II) trihydrate

2007 ◽  
Vol 63 (11) ◽  
pp. m2838-m2839 ◽  
Author(s):  
Naser Eltaher Eltayeb ◽  
Siang Guan Teoh ◽  
Suchada Chantrapromma ◽  
Hoong-Kun Fun ◽  
Kamarulazizi Ibrahim
Keyword(s):  
Schiff Base ◽  
Dihedral Angles ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Apical Position ◽  
Coordination Environment ◽  
Tetradentate Schiff Base ◽  
Solvent Water ◽  
Benzene Rings ◽  
Coordinated Water

In the title complex, [Zn(C20H14N2O4)(H2O)]·3H2O, the ZnII center is in an approximately square-pyramidal coordination environment with the two N and two O atoms of the tetradentate Schiff base ligand forming the basal plane and the coordinated water molecule in the apical position. Three solvent water molecules complete the asymmetric unit. The dihedral angles between the two outer benzene rings of the Schiff base and the central benzene ring are 12.64 (14) and 17.25 (14)°. In the crystal structure, intermolecular O—H...O hydrogen bonds link the molecules into sheets parallel to the ab plane.

scholarly journals Dimeric structures of quinol-dependent nitric oxide reductases (qNORs) revealed by cryo–electron microscopy

2019 ◽  
Vol 5 (8) ◽  
pp. eaax1803 ◽  
Author(s):  
Chai C. Gopalasingam ◽  
Rachel M. Johnson ◽  
George N. Chiduza ◽  
Takehiko Tosha ◽  
Masaki Yamamoto ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Electron Microscopy ◽  
Cytochrome C ◽  
Active Site ◽  
Proton Transport ◽  
Water Channel ◽  
Water Molecules ◽  
Cryo Electron Microscopy ◽  
Proton Source ◽  
Key Residues

Quinol-dependent nitric oxide reductases (qNORs) are membrane-integrated, iron-containing enzymes of the denitrification pathway, which catalyze the reduction of nitric oxide (NO) to the major ozone destroying gas nitrous oxide (N2O). Cryo–electron microscopy structures of active qNOR from Alcaligenes xylosoxidans and an activity-enhancing mutant have been determined to be at local resolutions of 3.7 and 3.2 Å, respectively. They unexpectedly reveal a dimeric conformation (also confirmed for qNOR from Neisseria meningitidis) and define the active-site configuration, with a clear water channel from the cytoplasm. Structure-based mutagenesis has identified key residues involved in proton transport and substrate delivery to the active site of qNORs. The proton supply direction differs from cytochrome c–dependent NOR (cNOR), where water molecules from the cytoplasm serve as a proton source similar to those from cytochrome c oxidase.

FTIR Study of the Retinal Schiff Base and Internal Water Molecules of Proteorhodopsin†

Biochemistry ◽  
2007 ◽  
Vol 46 (18) ◽  
pp. 5365-5373 ◽  
Author(s):  
Daisuke Ikeda ◽  
Yuji Furutani ◽  
Hideki Kandori
Keyword(s):  
Schiff Base ◽  
Water Molecules ◽  
Ftir Study ◽  
Internal Water

scholarly journals SEMICLASSICAL THEORY OF PROTON TRANSPORT IN ICE

1967 ◽  
Vol 45 (4) ◽  
pp. 1507-1516 ◽  
Author(s):  
Dong-Yun Kim ◽  
V. Hugo Schmidt
Keyword(s):  
Ion Mobility ◽  
Proton Transport ◽  
Electrostatic Interactions ◽  
Cutoff Frequency ◽  
Water Molecules ◽  
Collision Term ◽  
Lattice Vibrations ◽  
Semiclassical Theory ◽  
Boltzmann Transport ◽  
Proton Mobility

A method is described for calculating proton or other ion mobility which is applicable if mobility is limited by lattice scattering rather than by barrier jumping. The Boltzmann transport equation is used, with the collision term calculated from the electrostatic interactions between the mobile ion and the vibrating lattice. In particular the proton mobility in ice is calculated. The lattice vibrations are approximated by a Debye spectrum for translational vibrations of water molecules, plus an Einstein spectrum for modes in which protons vibrate almost as independent particles. Scattering by phonons somewhat below the Debye cutoff frequency is of the greatest importance in determining the mobility, and the proton modes have negligible effect. The calculated mobility agrees reasonably well with the experimental value.

Interaction of Internal Water Molecules with the Schiff Base in the L Intermediate of the Bacteriorhodopsin Photocycle†

Biochemistry ◽  
2002 ◽  
Vol 41 (11) ◽  
pp. 3803-3809 ◽  
Author(s):  
Akio Maeda ◽  
Sergei P. Balashov ◽  
Johan Lugtenburg ◽  
Michiel A. Verhoeven ◽  
Judith Herzfeld ◽  
...  
Keyword(s):  
Schiff Base ◽  
Water Molecules ◽  
Internal Water ◽  
Bacteriorhodopsin Photocycle

Proton Transport by Proteorhodopsin Requires that the Retinal Schiff Base Counterion Asp-97 Be Anionic†

Biochemistry ◽  
2003 ◽  
Vol 42 (21) ◽  
pp. 6582-6587 ◽  
Author(s):  
Andrei K. Dioumaev ◽  
Jennifer M. Wang ◽  
Zoltán Bálint ◽  
György Váró ◽  
Janos K. Lanyi
Keyword(s):  
Schiff Base ◽  
Proton Transport
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