Strongly Hydrogen-Bonded Schiff Base and Adjoining Polyene Twisting in the Retinal Chromophore of Schizorhodopsins

Biochemistry ◽  
2021 ◽  
Author(s):  
Tomomi Shionoya ◽  
Manish Singh ◽  
Misao Mizuno ◽  
Hideki Kandori ◽  
Yasuhisa Mizutani
Keyword(s):  
Schiff Base ◽  
Retinal Chromophore ◽  
Hydrogen Bonded

A facile biomimetic catalytic activity through hydrogen atom abstraction by the secondary coordination sphere in manganese(iii) complexes

2020 ◽  
Vol 49 (40) ◽  
pp. 14216-14230
Author(s):  
Narayan Ch. Jana ◽  
Paula Brandão ◽  
Antonio Frontera ◽  
Anangamohan Panja
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Hydrogen Atom ◽  
Coordination Sphere ◽  
Hydrogen Atom Abstraction ◽  
Schiff Base Ligands ◽  
Secondary Coordination Sphere ◽  
Catalytic Reactivity ◽  
Hydrogen Bonded

Four hydrogen bonded supramolecular manganese(iii) complexes with N3O donor Schiff base ligands and a facile biomimetic catalytic reactivity through hydrogen atom abstraction by the secondary coordination sphere have been reported.

scholarly journals Lokiarchaeota archaeon schizorhodopsin-2 (LaSzR2) is an inward proton pump displaying a characteristic feature of acid-induced spectral blue-shift

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Keiichi Kojima ◽  
Susumu Yoshizawa ◽  
Masumi Hasegawa ◽  
Masaki Nakama ◽  
Marie Kurihara ◽  
...  
Keyword(s):  
Schiff Base ◽  
Proton Pump ◽  
Flash Photolysis ◽  
Blue Shift ◽  
Spectroscopic Studies ◽  
Spectral Shift ◽  
Bulk Solution ◽  
Proton Pumps ◽  
Ph Titration ◽  
Retinal Chromophore

AbstractThe photoreactive protein rhodopsin is widespread in microorganisms and has a variety of photobiological functions. Recently, a novel phylogenetically distinctive group named ‘schizorhodopsin (SzR)’ has been identified as an inward proton pump. We performed functional and spectroscopic studies on an uncharacterised schizorhodopsin from the phylum Lokiarchaeota archaeon. The protein, LaSzR2, having an all-trans-retinal chromophore, showed inward proton pump activity with an absorption maximum at 549 nm. The pH titration experiments revealed that the protonated Schiff base of the retinal chromophore (Lys188, pKa = 12.3) is stabilised by the deprotonated counterion (presumably Asp184, pKa = 3.7). The flash-photolysis experiments revealed the presence of two photointermediates, K and M. A proton was released and uptaken from bulk solution upon the formation and decay of the M intermediate. During the M-decay, the Schiff base was reprotonated by the proton from a proton donating residue (presumably Asp172). These properties were compared with other inward (SzRs and xenorhodopsins, XeRs) and outward proton pumps. Notably, LaSzR2 showed acid-induced spectral ‘blue-shift’ due to the protonation of the counterion, whereas outward proton pumps showed opposite shifts (red-shifts). Thus, we can distinguish between inward and outward proton pumps by the direction of the acid-induced spectral shift.

A theoretical insight on the rigid hydrogen-bonded network in the solid state structure of two zinc(ii) complexes and their strong fluorescence behaviors

CrystEngComm ◽  
2020 ◽  
Vol 22 (17) ◽  
pp. 3005-3019 ◽  
Author(s):  
Ipsita Mondal ◽  
Tanmoy Basak ◽  
Snehasis Banerjee ◽  
Shouvik Chattopadhyay
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Selective Detection ◽  
State Structure ◽  
Strong Fluorescence ◽  
Solid State Structure ◽  
Reduced Schiff Base ◽  
Theoretical Insight ◽  
Hydrogen Bonded

A reduced Schiff base used as a fluorescence chemo-sensor for selective detection of zinc(ii). Strong fluorescence behaviors of two zinc(ii) complexes are correlated with the presence of a rigid hydrogen-bonded network in their solid state structure.

scholarly journals Stabilization of two conformers via intra- or inter-molecular hydrogen bonds in a dinuclear vanadium(v) complex with a pendant Schiff base: theoretical insight

RSC Advances ◽  
2019 ◽  
Vol 9 (60) ◽  
pp. 35165-35175 ◽  
Author(s):  
Snehasish Thakur ◽  
Michael G. B. Drew ◽  
Antonio Franconetti ◽  
Antonio Frontera ◽  
Shouvik Chattopadhyay
Keyword(s):  
Density Functional Theory ◽  
Schiff Base ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Molecular Hydrogen ◽  
Density Functional ◽  
Functional Theory ◽  
Theoretical Insight ◽  
Hydrogen Bonded

Two different hydrogen bonded conformers coexist in a synthesized dinuclear oxovanadium(v) Schiff base. Density functional theory (DFT) calculations were utilized to calculate the energies involved in two different conformers.

Water-Mediated Hydrogen-Bonded Network on the Cytoplasmic Side of the Schiff Base of the L Photointermediate of Bacteriorhodopsin†

Biochemistry ◽  
2003 ◽  
Vol 42 (48) ◽  
pp. 14122-14129 ◽  
Author(s):  
Akio Maeda ◽  
Judith Herzfeld ◽  
Marina Belenky ◽  
Richard Needleman ◽  
Robert B. Gennis ◽  
...  
Keyword(s):  
Schiff Base ◽  
Cytoplasmic Side ◽  
Hydrogen Bonded
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