Synthesis of Dihydrothiophenes and Thiophenes by the Strategic Use of 2-Vinylidene-1,3-dithiolane as a Masked Thiolate Anion

2014 ◽  
Vol 2014 (5) ◽  
pp. 924-927 ◽  
Author(s):  
Zhongxue Fang ◽  
Peiqiu Liao ◽  
Zonglian Yang ◽  
Yeming Wang ◽  
Biying Zhou ◽  
...  
Keyword(s):  
Thiolate Anion

The thiolate anion as a nucleophile Part V. Reactions of ethanedithiol

1976 ◽  
Vol 7 (4) ◽  
pp. 427-429 ◽  
Author(s):  
Bonita C. Musial ◽  
Michael E. Peach
Keyword(s):  
Thiolate Anion

Kinetik der Reaktion von 2.4-Dinitrofluorbenzol mit Imidazol-, SH- und Imidazol-SH-Verbindungen / Kinetics of the Reaction of 2,4-dinitro-1-fluorobenzene with Imidazole-, SH- and Imidazole-SH-compounds

1971 ◽  
Vol 26 (10) ◽  
pp. 1010-1016 ◽  
Author(s):  
Renate Voigt ◽  
Helmut Wenck ◽  
Friedhelm Schneider
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Reaction Rate ◽  
Ph Dependence ◽  
First Order ◽  
Molecular Transfer ◽  
Thiolate Anion ◽  
Nucleophilic Reactivity ◽  
Kinetics Of ◽  
Lindley Equation

First order rate constants of the reaction of a series of SH-, imidazole- and imidazole/SH-compounds with FDNB as well as their pH- and temperature dependence were determined. Some of the tested imidazole/SH-compounds exhibit a higher nucleophilic reactivity as is expected on the basis of their pKSH-values. This enhanced reactivity is caused by an activation of the SH-groups by a neighbouring imidazole residue. The pH-independent rate constants were calculated using the Lindley equation.The kinetics of DNP-transfer from DNP-imidazole to SH-compounds were investigated. The pH-dependence of the reaction displays a maximum curve. Donor in this reaction is the DNP-imidazolecation and acceptor the thiolate anion.The reaction rate of FDNB with imidazole derivatives is two to three orders of magnitude slower than with SH-compounds.No inter- or intra-molecular transfer of the DNP-residue from sulfure to imidazole takes place.

scholarly journals A dynamic Asp–Arg interaction is essential for catalysis in microsomal prostaglandin E2 synthase

2016 ◽  
Vol 113 (4) ◽  
pp. 972-977 ◽  
Author(s):  
Joseph S. Brock ◽  
Mats Hamberg ◽  
Navisraj Balagunaseelan ◽  
Michael Goodman ◽  
Ralf Morgenstern ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Anticancer Agents ◽  
Site Directed Mutagenesis ◽  
Lipid Mediator ◽  
Prostaglandin E ◽  
Hydrogen Bond Donor ◽  
Anion Formation ◽  
Functional Roles ◽  
Conformational Ensembles ◽  
Thiolate Anion

Microsomal prostaglandin E2 synthase type 1 (mPGES-1) is responsible for the formation of the potent lipid mediator prostaglandin E2 under proinflammatory conditions, and this enzyme has received considerable attention as a drug target. Recently, a high-resolution crystal structure of human mPGES-1 was presented, with Ser-127 being proposed as the hydrogen-bond donor stabilizing thiolate anion formation within the cofactor, glutathione (GSH). We have combined site-directed mutagenesis and activity assays with a structural dynamics analysis to probe the functional roles of such putative catalytic residues. We found that Ser-127 is not required for activity, whereas an interaction between Arg-126 and Asp-49 is essential for catalysis. We postulate that both residues, in addition to a crystallographic water, serve critical roles within the enzymatic mechanism. After characterizing the size or charge conservative mutations Arg-126–Gln, Asp-49–Asn, and Arg-126–Lys, we inferred that a crystallographic water acts as a general base during GSH thiolate formation, stabilized by interaction with Arg-126, which is itself modulated by its respective interaction with Asp-49. We subsequently found hidden conformational ensembles within the crystal structure that correlate well with our biochemical data. The resulting contact signaling network connects Asp-49 to distal residues involved in GSH binding and is ligand dependent. Our work has broad implications for development of efficient mPGES-1 inhibitors, potential anti-inflammatory and anticancer agents.

scholarly journals A Thiolate Anion Buried within the Hydrocarbon Ruler Perturbs PagP Lipid Acyl Chain Selection

Biochemistry ◽  
2010 ◽  
Vol 49 (11) ◽  
pp. 2368-2379 ◽  
Author(s):  
M. Adil Khan ◽  
Joel Moktar ◽  
Patrick J. Mott ◽  
Russell E. Bishop
Keyword(s):  
Acyl Chain ◽  
Thiolate Anion
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