scholarly journals Halide-selective, proton-coupled anion transport by phenylthiosemicarbazones

2021 ◽  
Author(s):  
Ethan N.W. Howe ◽  
Vai-Vai Tiffany Chang ◽  
Xin Wu ◽  
Mohamed Fares ◽  
William Lewis ◽  
...  
Keyword(s):  
Anion Transport ◽  
Crystallographic Analysis ◽  
Nitrate Transport ◽  
X Ray ◽  
Anion Transporters ◽  
Protonation Equilibrium ◽  
Intramolecular Hydrogen ◽  
Rate Limiting ◽  
High Chloride ◽  
Surprising Finding

Phenylthiosemicarbazones (PTSCs) are proton-coupled anion transporters with pH-switchable behaviour known to be regulated by an imine protonation equilibrium. Previously, chloride/nitrate exchange by PTSCs was found to be inactive at pH 7.2 due to locking of the thiourea anion binding site by an intramolecular hydrogen bond, and switched ON upon imine protonation at pH 4.5. The rate-determining process of the pH switch, however, was not examined. We here develop a new series of PTSCs and demonstrate their conformational behaviour by X-ray crystallographic analysis and pH-switchable anion transport properties by liposomal assays. We report the surprising finding that the protonated PTSCs are extremely selective for halides over oxyanions in membrane transport. Owing to the high chloride over nitrate selectivity, the pH-dependent chloride/nitrate exchange of PTSCs originates from the rate-limiting nitrate transport process being inhibited at neutral pH.

scholarly journals Halide-selective, proton-coupled anion transport by phenylthiosemicarbazones

2021 ◽  
Author(s):  
Ethan N.W. Howe ◽  
Vai-Vai Tiffany Chang ◽  
Xin Wu ◽  
Mohamed Fares ◽  
William Lewis ◽  
...  
Keyword(s):  
Anion Transport ◽  
Crystallographic Analysis ◽  
Nitrate Transport ◽  
X Ray ◽  
Anion Transporters ◽  
Protonation Equilibrium ◽  
Intramolecular Hydrogen ◽  
Rate Limiting ◽  
High Chloride ◽  
Surprising Finding

Phenylthiosemicarbazones (PTSCs) are proton-coupled anion transporters with pH-switchable behaviour known to be regulated by an imine protonation equilibrium. Previously, chloride/nitrate exchange by PTSCs was found to be inactive at pH 7.2 due to locking of the thiourea anion binding site by an intramolecular hydrogen bond, and switched ON upon imine protonation at pH 4.5. The rate-determining process of the pH switch, however, was not examined. We here develop a new series of PTSCs and demonstrate their conformational behaviour by X-ray crystallographic analysis and pH-switchable anion transport properties by liposomal assays. We report the surprising finding that the protonated PTSCs are extremely selective for halides over oxyanions in membrane transport. Owing to the high chloride over nitrate selectivity, the pH-dependent chloride/nitrate exchange of PTSCs originates from the rate-limiting nitrate transport process being inhibited at neutral pH.

scholarly journals Remarkable Conversion of 2-Thioxo-2,3-dihydroquinazolin-4(1H)-ones into the Corresponding Quinazoline-2,4(1H,3H)-diones: Spectroscopic Analysis and X-Ray Crystallography

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Adel S. El-Azab ◽  
Nasr Y. Khalil ◽  
Alaa A.-M. Abdel-Aziz
Keyword(s):  
Spectroscopic Analysis ◽  
Crystallographic Analysis ◽  
Synthetic Method ◽  
Visible Spectroscopy ◽  
X Ray ◽  
X Ray Crystallography ◽  
Mild Conditions ◽  
Uv Visible ◽  
Independent Molecules ◽  
Intramolecular Hydrogen

A simple and efficient new synthetic method to obtain 3-substituted quinazolin-2,4-diones 9–16 by the reaction of 3-substituted 2-thioxo-quinazolin-4-ones 1–8 with sodamide under mild conditions was presented. The structure of the newly synthesized compounds was determined by infrared spectroscopy, UV-visible spectroscopy, nuclear magnetic resonance, and single-crystal X-ray crystallographic analysis. The crystal structure of 6-methyl-3-phenylquinazoline-2,4(1H,3H)-dione (11) [C15H12N2O2: MF = 252.27, triclinic, P-1, a = 7.8495 (13) Å, b = 12.456 (2) Å, c = 13.350 (2) Å, α = 103.322 (3)°, β = 90.002 (3)°, γ = 102.671 (4)°, V = 1237.5 (3) Å3, Z = 4, R = 0.0592, wR = 0.1699, S = 1.039] was determined. In the crystal cell, two identical conformers of compound 11 were found connected by intramolecular hydrogen bonds, responsible for the favourable occurrence of these two independent molecules.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Purification, crystallization and X-ray crystallographic analysis of ATPase domain in transcription regulator DmpR

2019 ◽  
Vol 7 (2) ◽  
pp. 52-55
Author(s):  
Su-Jin Lee ◽  
In-Young Baek ◽  
Yan An ◽  
Woo-Chan Ahn ◽  
Kwang-Hyun Park ◽  
...  
Keyword(s):  
Crystallographic Analysis ◽  
Atpase Domain ◽  
X Ray ◽  
Transcription Regulator

Purification, crystallization and X-ray crystallographic analysis of methylglyoxal reductase Gre2 from Candida albicans

2019 ◽  
Vol 7 (2) ◽  
pp. 42-46 ◽  
Author(s):  
Giang Thu Nguyen ◽  
Shinae Kim ◽  
Hang-Suk Chun ◽  
Woo-Keun Kim ◽  
Jeong Ho Chang
Keyword(s):  
Candida Albicans ◽  
Crystallographic Analysis ◽  
X Ray

(thf)2Ln(Ge9{Si(SiMe3)3}3)2 (Ln = Eu, Sm): the first coordination of metalloid germanium clusters to lanthanides

2021 ◽  
Author(s):  
Andreas Schnepf ◽  
Svetlana Klementyeva ◽  
Claudio Schrenk ◽  
Marat M Khusniyarov ◽  
Minghui Zhang
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Crystallographic Analysis ◽  
Rare Earth Complexes ◽  
Group 14 ◽  
X Ray ◽  
Germanium Clusters

We report the synthesis, structure and magnetic properties of the first rare earth complexes of metalloid group 14 clusters [(thf)2Ln(Ge9Hyp3)2] (Ln = Eu, Sm, Hyp = Si(SiMe3)3). X-ray crystallographic analysis...

New alkaloids from Capparis spinosa: Structure and X-ray crystallographic analysis

2010 ◽  
Vol 123 (3) ◽  
pp. 705-710 ◽  
Author(s):  
Tao Yang ◽  
Chang-hong Wang ◽  
Gui-xin Chou ◽  
Tao Wu ◽  
Xue-mei Cheng ◽  
...  
Keyword(s):  
Crystallographic Analysis ◽  
X Ray ◽  
Capparis Spinosa

scholarly journals Two alternative modes for optimizing nylon-6 byproduct hydrolytic activity from a carboxylesterase with a β-lactamase fold: X-ray crystallographic analysis of directly evolved 6-aminohexanoate-dimer hydrolase

2009 ◽  
Vol 18 (8) ◽  
pp. 1662-1673 ◽  
Author(s):  
Taku Ohki ◽  
Naoki Shibata ◽  
Yoshiki Higuchi ◽  
Yasuyuki Kawashima ◽  
Masahiro Takeo ◽  
...  
Keyword(s):  
Hydrolytic Activity ◽  
Nylon 6 ◽  
Crystallographic Analysis ◽  
X Ray

Crystallization and preliminary X-ray crystallographic analysis of SP1, a novel chaperone-like protein

2003 ◽  
Vol 59 (3) ◽  
pp. 512-514 ◽  
Author(s):  
Wangxia Wang ◽  
Or Dgany ◽  
Orly Dym ◽  
Arie Altman ◽  
Oded Shoseyov ◽  
...  
Keyword(s):  
Crystallographic Analysis ◽  
X Ray
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