Exploring the Active Center of Human Acetylcholinesterase with Stereomers of an Organophosphorus Inhibitor with Two Chiral Centers†

Biochemistry ◽  
1999 ◽  
Vol 38 (10) ◽  
pp. 3055-3066 ◽  
Author(s):  
Arie Ordentlich ◽  
Dov Barak ◽  
Chanoch Kronman ◽  
Hendrik P. Benschop ◽  
Leo P. A. De Jong ◽  
...  
Keyword(s):  
Active Center ◽  
Chiral Centers ◽  
Organophosphorus Inhibitor

Kinetic Study of the Effect of Heparin on the Amidase Activity of Trypsin, Plasmin and Urokinase

1983 ◽  
Vol 49 (03) ◽  
pp. 199-203 ◽  
Author(s):  
V M Yomtova ◽  
N A Stambolieva ◽  
B M Blagoev
Keyword(s):  
Kinetic Study ◽  
Active Center ◽  
Simultaneous Presence ◽  
Amidase Activity ◽  
Competitive Inhibitors ◽  
Uncompetitive Inhibitor

SummaryIt was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and α-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2×10-6 M), plasmin (Ki = 4.9×10-6 M) and urokinase (Ki = l.0×10-7 M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.

Matrix metalloproteinases: structure, functions and genetic polymorphism

2017 ◽  
pp. 14-23
Author(s):  
А.С. Шадрина ◽  
И.В. Терешкина ◽  
Я.З. Плиева ◽  
Д.Н. Кушлинский ◽  
Д.О. Уткин ◽  
...  
Keyword(s):  
Genetic Polymorphism ◽  
Matrix Metalloproteinases ◽  
Active Center ◽  
Human Body ◽  
Enzymatic Catalysis ◽  
Structure Functions ◽  
Zinc Ion ◽  
Etiological Factors ◽  
Mmp Genes

Матриксные металлопротеиназы (ММП) - ферменты класса гидролаз, осуществляющие ферментативный катализ с помощью связанного в активном центре иона цинка. Функции ММП разнообразны, и нарушение баланса их активности может быть одним из этиологических факторов различных заболеваний. В данном обзоре рассмотрена классификация ММП человека, особенности их структуры и регуляции, а также роль в физиологических и патологических процессах в организме человека. Приведен перечень наиболее изученных на настоящий момент полиморфных вариантов генов MMП, описаны их функциональные эффекты и представлены результаты ассоциативных исследований. Matrix metalloproteinases (MMPs) are enzymes of the hydrolase class that carry out enzymatic catalysis with the help of a zinc ion bound in the active center. MMP functions are diverse, and a disturbance in the balance of their activity may be one of the etiological factors of various diseases. In this review, the classification of human MMP, the features of their structure and regulation, as well as the role in physiological and pathological processes in the human body are considered. A list of the most studied polymorphic versions of MMP genes has been given, their functional effects have been described, and the results of associative studies have been presented.

Self-Assembly of a Chiral Cubic Three-Connected Net from the High Symmetry Molecules C60 and SnI4

2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava
Keyword(s):  
Organic Synthesis ◽  
Self Assembly ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
High Symmetry ◽  
Molecular Chirality ◽  
Chiral Materials ◽  
Self Assembled ◽  
Chiral Centers

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.

Three-Component [1+1+1] Cyclopropanation with Ruthenium(II)

2018 ◽  
Author(s):  
Tanner C. Jankins ◽  
Robert R. Fayzullin ◽  
Eugene Khaskin
Keyword(s):  
Quaternary Carbon ◽  
Poor Control ◽  
One Step ◽  
Synthetic Routes ◽  
Mechanistic Investigations ◽  
Chiral Centers ◽  
Metal Catalyzed ◽  
The Right ◽  
Substituted Cyclopropanes

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal catalyzed carbene attack on olefins. Under the current protocol, various alcohols are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. 22 examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multi-step, linear routes that proceed with overall low yields and poor control of stereochemistry. Experimental mechanistic investigations suggest initial metal-catalyzed dehydrogenation of the alcohol substrate and catalyst independent stepwise attack of two equivalents of sulfone on the aldehyde under basic conditions. While the Ru(II) is only responsible for the initial dehydrogenation step, the rate of aldehyde formation is crucial to maintaining the right balance of intermediates needed to afford the cyclopropane product.

Enantioselective Multi-Component Cyclopropane Synthesis Enabled by Cu-Catalyzed Cyclopropene Carbometallation with Organoboron Reagent

2018 ◽  
Author(s):  
Zhanyu Li ◽  
Mengru Zhang ◽  
Yu Zhang ◽  
Shuang Liu ◽  
Jinbo Zhao ◽  
...  
Keyword(s):  
Carbon Source ◽  
Stereoselective Synthesis ◽  
Organometallic Reagents ◽  
Preliminary Results ◽  
Quaternary Center ◽  
Chiral Centers ◽  
Substituted Cyclopropanes ◽  
Proof Of Principle

Deployment of organoboron in lieu of the strongly basic <br>organometallic reagents as carbon source in Cu-catalyzed <br>cyclopropene carbometallation opens unprecedented three-<br>component reactivity for stereoselective synthesis of poly-substituted cyclopropanes. A proof-of-principle demonstration of this novel carbometallation strategy is presented herein for a highly convergent access to poly-substituted aminocyclopropane framework via <br>carboamination. Preliminary results on asymmetric desymmetrization with commercial bisphosphine ligands attained high levels of enantioselection, offering a straightforward access to enantioenriched aminocyclopropanes bearing all-three chiral centers, including an all-carbon quaternary center. This strategy may underpin a host of novel synthetic protocols for poly-substituted cyclopropanes. <br>

scholarly journals Characterization of the Active Center of Thioredoxin Reductase

1967 ◽  
Vol 242 (22) ◽  
pp. 5232-5236 ◽  
Author(s):  
Giuliana Zanetti ◽  
Charles H. Williams
Keyword(s):  
Active Center ◽  
Thioredoxin Reductase

scholarly journals The sigma subunit conserved region 3 is part of “5'-face” of active center of Escherichia coli RNA polymerase.

1994 ◽  
Vol 269 (33) ◽  
pp. 20826-20828 ◽  
Author(s):  
K. Severinov ◽  
D. Fenyö ◽  
E. Severinova ◽  
A. Mustaev ◽  
B.T. Chait ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Active Center ◽  
Conserved Region ◽  
Sigma Subunit

scholarly journals Mechanism of SARS-CoV-2 polymerase stalling by remdesivir

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Goran Kokic ◽  
Hauke S. Hillen ◽  
Dimitry Tegunov ◽  
Christian Dienemann ◽  
Florian Seitz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Binding Site ◽  
Molecular Mechanism ◽  
Active Center ◽  
Rna Synthesis ◽  
Active Form ◽  
Nucleoside Triphosphate ◽  
Rna Dependent Rna Polymerase ◽  
Cryo Electron Microscopy

AbstractRemdesivir is the only FDA-approved drug for the treatment of COVID-19 patients. The active form of remdesivir acts as a nucleoside analog and inhibits the RNA-dependent RNA polymerase (RdRp) of coronaviruses including SARS-CoV-2. Remdesivir is incorporated by the RdRp into the growing RNA product and allows for addition of three more nucleotides before RNA synthesis stalls. Here we use synthetic RNA chemistry, biochemistry and cryo-electron microscopy to establish the molecular mechanism of remdesivir-induced RdRp stalling. We show that addition of the fourth nucleotide following remdesivir incorporation into the RNA product is impaired by a barrier to further RNA translocation. This translocation barrier causes retention of the RNA 3ʹ-nucleotide in the substrate-binding site of the RdRp and interferes with entry of the next nucleoside triphosphate, thereby stalling RdRp. In the structure of the remdesivir-stalled state, the 3ʹ-nucleotide of the RNA product is matched and located with the template base in the active center, and this may impair proofreading by the viral 3ʹ-exonuclease. These mechanistic insights should facilitate the quest for improved antivirals that target coronavirus replication.

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