A computational study of pyrazinamide: Tautomerism, acid–base properties, micro-solvation effects and acid hydrolysis mechanism

The 20S Proteasome is a macromolecule responsible for the chemical step in the ubiquitin-proteasome system of degrading unnecessary and unused proteins of the cell. It plays a central role both in the rapid growth of cancer cells as well as in viral infection cycles. Herein, we present a computational study of the acid-base equilibria in an active site of the human proteasome, an aspect which is often neglected despite the crucial role protons play in the catalysis. As example substrates, we take the inhibition by epoxy and boronic acid containing warheads. We have combined cluster quantum mechanical calculations, replica exchange molecular dynamics and Bayesian optimization of non-bonded potential terms in the inhibitors. In relation to the latter, we propose an easily scalable approach to the reevaluation of non-bonded potentials making use of QM/MM dynamics information. Our results show that coupled acid-base equilibria need to be considered when modeling the inhibition mechanism. The coupling between a neighboring lysine and the reacting threonine is not affected by the presence of the inhibitor.

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Acid-base properties of borates under kraft pulp cooking conditions

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2003-18-01-p090-094 ◽

2003 ◽

Vol 18 (1) ◽

pp. 90-94

Author(s):

Per Ulmgren ◽

Disa Tormund

Keyword(s):

Kraft Pulp ◽

Acid Base ◽

Cooking Conditions ◽

Base Properties

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Effects of Acid-Base Properties of Oxide Catalysts on Transformation of 1,2-Propylene Glycol

CHINESE JOURNAL OF CATALYSIS (CHINESE VERSION) ◽

10.3724/sp.j.1088.2010.91014 ◽

2010 ◽

Vol 31 (4) ◽

pp. 441-446

Author(s):

Zhengxi YU ◽

Lei XU ◽

Xinzhi ZHANG ◽

Zhongmin LIU

Keyword(s):

Propylene Glycol ◽

Oxide Catalysts ◽

Acid Base ◽

Base Properties

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THE ACID-BASE PROPERTIES OF CLAY MINERALS AS A POTENTIAL BUFFER FOR SEDIMENT PORE WATER PH AND CARBONATE SATURATION DURING MICROBIAL IRON REDUCTION

10.1130/abs/2018am-324490 ◽

2018 ◽

Author(s):

N. Tanner Mills ◽

◽

Julia S. Reece ◽

Michael M. Tice

Keyword(s):

Clay Minerals ◽

Pore Water ◽

Iron Reduction ◽

Acid Base ◽

Sediment Pore Water ◽

Microbial Iron Reduction ◽

Water Ph ◽

Base Properties

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Acid-base properties of 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822882 ◽

1982 ◽

Vol 47 (11) ◽

pp. 2882-2889

Author(s):

Nadezhda Likhareva ◽

Ladislav Šůcha ◽

Miloslav Suchánek

Keyword(s):

Computer Program ◽

Dissociation Constants ◽

Acid Base ◽

New Compounds ◽

Base Properties

Two new compounds from the formazan series, viz. 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan, were prepared, and the dissociation constants and molar absorptivities of all of their acid-base species were determined spectrophotometrically employing the SPEKTFOT computer program.

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Acid-base properties of metals and glasses of Na2O.P2O5-xB2O3 system

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19842355 ◽

1984 ◽

Vol 49 (10) ◽

pp. 2355-2362 ◽

Cited By ~ 2

Author(s):

Juraj Leško ◽

Marie Dorušková ◽

Jan Tržil

Keyword(s):

Boron Oxide ◽

A Priori ◽

Optical Basicity ◽

Galvanic Cell ◽

Acid Base ◽

Tetrahedral Configuration ◽

Relative Basicity ◽

Base Theory ◽

Base Properties

Boron oxide in the Na2O.P2O5-x B2O3 system behaves as a Lux base. Its addition to Na2O.P2O5 brings about transformation of a Co(II) indicator from octahedral to tetrahedral configuration, increase in the optical basicity ΛPb(II), increase in the relative basicity of the melt as determined by means of a galvanic cell, and depolymerization reactions releasing PO43- ions. In the Na2O-B2O3 system free of P2O5, boron oxide behaves as a Lux acid. The amphoretic nature of B2O3 is explained in terms of Lux's acid-base theory extended in analogy with the protolysis theory. The theoretical optical basicity values do not indicate the amphoretic behaviour of B2O3 because in this approach boron oxide is a priori regarded as more acidic than Na2O.P2O5.

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