Structural Changes of Water in the Schiff Base Region of Bacteriorhodopsin:  Proposal of a Hydration Switch Model†

Biochemistry ◽  
2003 ◽  
Vol 42 (8) ◽  
pp. 2300-2306 ◽  
Author(s):  
Taro Tanimoto ◽  
Yuji Furutani ◽  
Hideki Kandori
Keyword(s):  
Schiff Base ◽  
Structural Changes ◽  
Base Region

Structural Changes in the Schiff Base Region of Squid Rhodopsin upon Photoisomerization Studied by Low-Temperature FTIR Spectroscopy†

Biochemistry ◽  
2006 ◽  
Vol 45 (9) ◽  
pp. 2845-2851 ◽  
Author(s):  
Toru Ota ◽  
Yuji Furutani ◽  
Akihisa Terakita ◽  
Yoshinori Shichida ◽  
Hideki Kandori
Keyword(s):  
Schiff Base ◽  
Low Temperature ◽  
Ftir Spectroscopy ◽  
Structural Changes ◽  
Base Region

scholarly journals Structural changes in a Schiff base molecular assembly initiated by scanning tunneling microscopy tip

2016 ◽  
Vol 27 (33) ◽  
pp. 335601 ◽  
Author(s):  
A Tomak ◽  
C Bacaksiz ◽  
G Mendirek ◽  
H Sahin ◽  
D Hur ◽  
...  
Keyword(s):  
Schiff Base ◽  
Scanning Tunneling Microscopy ◽  
Structural Changes ◽  
Molecular Assembly ◽  
Scanning Tunneling ◽  
Tunneling Microscopy

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

scholarly journals Zwitterionic Acetylated Cellulose Nanofibrils

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3147 ◽  
Author(s):  
Jowan Rostami ◽  
Aji P. Mathew ◽  
Ulrica Edlund
Keyword(s):  
Acetic Acid ◽  
Schiff Base ◽  
Reaction Time ◽  
Structural Changes ◽  
Glacial Acetic Acid ◽  
Cellulose Nanofibrils ◽  
Periodate Oxidation ◽  
Hydroxyl Groups ◽  
Borohydride Reduction ◽  
Short Reaction Time

A strategy is devised to synthesize zwitterionic acetylated cellulose nanofibrils (CNF). The strategy included acetylation, periodate oxidation, Schiff base reaction, borohydride reduction, and a quaternary ammonium reaction. Acetylation was performed in glacial acetic acid with a short reaction time of 90 min, yielding, on average, mono-acetylated CNF with hydroxyl groups available for further modification. The products from each step were characterized by FTIR spectroscopy, ζ-potential, SEM-EDS, AFM, and titration to track and verify the structural changes along the sequential modification route.

Difference fourier maps reveal structural changes for intermediates in the bacteriorhodopsin photocycle

1995 ◽  
Vol 53 ◽  
pp. 832-833
Author(s):  
R. M. Glaeser ◽  
B.-G. Han ◽  
F. M. Hendrickson ◽  
J. Vonck
Keyword(s):  
Schiff Base ◽  
Cell Membrane ◽  
Structural Changes ◽  
Proton Pumping ◽  
Schematic Model ◽  
Functional Changes ◽  
Resonance Raman Spectra ◽  
Proton Movement ◽  
Difference Fourier ◽  
Bacteriorhodopsin Photocycle

Bacteriorhodopsin (bR) is a light-driven proton pump that exists in the cell membrane of halobacteria. Proton pumping across the membrane is achieved through a photochemical cycle that involves several discrete structural intermediates. These intermediates are characterized by discrete changes in the visible and the resonance Raman spectra of the chromophore (a retinal group linked to the protein by a Schiff base) and in the infrared spectrum of the protein itself. Protein structural changes are thought to change access to the protonated Schiff base via inward and outward facing aqueous channels, respectively, during different stages of the photocycle, thus allowing for vectorial proton movement across the cell membrane. A schematic model of the functional changes in structure that occur throughout the photocycle is given by the cartoon shown in Figure 1.We have recently begun electron diffraction studies on the intermediates in the bR photocycle, with the goal of using difference Fourier maps to see directly the structural changes that correspond to the previously observed spectroscopic changes.

Strongly hydrogen-bonded water molecules in the Schiff base region of rhodopsins

2005 ◽  
Vol 4 (9) ◽  
pp. 661 ◽  
Author(s):  
Yuji Furutani ◽  
Mikihiro Shibata ◽  
Hideki Kandori
Keyword(s):  
Schiff Base ◽  
Water Molecules ◽  
Base Region ◽  
Hydrogen Bonded

scholarly journals Crystal structure ofHalobacterium salinarumhalorhodopsin with a partially depopulated primary chloride-binding site

2016 ◽  
Vol 72 (9) ◽  
pp. 692-699 ◽  
Author(s):  
Madeleine Schreiner ◽  
Ramona Schlesinger ◽  
Joachim Heberle ◽  
Hartmut H. Niemann
Keyword(s):  
Schiff Base ◽  
Binding Site ◽  
Conformational Changes ◽  
Structural Changes ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Halobacterium Salinarum ◽  
Chloride Binding ◽  
High Ph ◽  
Chloride Depletion

The transmembrane pump halorhodopsin in halophilic archaea translocates chloride ions from the extracellular to the cytoplasmic side upon illumination. In the ground state a tightly bound chloride ion occupies the primary chloride-binding site (CBS I) close to the protonated Schiff base that links the retinal chromophore to the protein. The light-triggeredtrans–cisisomerization of retinal causes structural changes in the protein associated with movement of the chloride ion. In reverse, chemical depletion of CBS I inNatronomonas pharaonishalorhodopsin (NpHR) through deprotonation of the Schiff base results in conformational changes of the protein: a state thought to mimic late stages of the photocycle. Here, crystals ofHalobacterium salinarumhalorhodopsin (HsHR) were soaked at high pH to provoke deprotonation of the Schiff base and loss of chloride. The crystals changed colour from purple to yellow and the occupancy of CBS I was reduced from 1 to about 0.5. In contrast toNpHR, this chloride depletion did not cause substantial conformational changes in the protein. Nevertheless, two observations indicate that chloride depletion could eventually result in structural changes similar to those found inNpHR. Firstly, the partially chloride-depleted form ofHsHR has increased normalizedBfactors in the region of helix C that is close to CBS I and changes its conformation inNpHR. Secondly, prolonged soaking ofHsHR crystals at high pH resulted in loss of diffraction. In conclusion, the conformation of the chloride-free protein may not be compatible with this crystal form ofHsHR despite a packing arrangement that hardly restrains helices E and F that presumably move during ion transport.

scholarly journals The photoactive site modulates current rectification and channel closing in the natural anion channelrhodopsin GtACR1

2019 ◽  
Author(s):  
Oleg A. Sineshchekov ◽  
Elena G. Govorunova ◽  
Hai Li ◽  
Xin Wang ◽  
John L. Spudich
Keyword(s):  
Crystal Structure ◽  
Schiff Base ◽  
Chloride Conductance ◽  
Base Region ◽  
Channel Processes ◽  
Conducting Channel ◽  
Channel Opening ◽  
Guillardia Theta ◽  
Current Rectification ◽  
Electrostatic Perturbation

ABSTRACTThe crystal structure of GtACR1 from Guillardia theta revealed an intramolecular tunnel predicted to expand to form the anion-conducting channel upon photoactivation (Li et al. 2019). The location of the retinylidene photoactive site within the tunnel raised the question of whether, in addition to triggering channel opening by photoisomerization, the site also participates in later channel processes. Here we demonstrate the involvement of the photoactive site in chloride conductance and channel closing. Electrostatic perturbation of the photoactive retinylidene Schiff base region by glutamate substitutions alters the rectification of the photocurrent as well as channel closing kinetics. Substitutions on opposite sides of the photoactive site causes opposite changes, with channel closing kinetically correlated with Schiff base deprotonation, and the extent of these effects closely correlate with distance of the introduced glutamyl residue from the photoactive site.

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