Results 271 to 280 of about 136,042 (297)
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Low barrier hydrogen bonds within salicylate mono-anions
Tetrahedron, 2001Abstract Progressive incorporation of electron-withdrawing substituents into the aromatic ring of salicylic acid selectively acidifies the ArOH group, until the intrinsic pKa values of the ArOH and ArCO2H groups become matched, as in the case of 3-chloro-5-nitrosalicylic acid.
Layne A. Morsch, William L. Mock
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Ab Initio QM/MM Study of the Citrate Synthase Mechanism. A Low-Barrier Hydrogen Bond Is not Involved
, 2000 Adrian J. Mulholland +2 more
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Biochemistry, 1998
The basicity of His 57-Nepsilon2 within the low-barrier hydrogen-bonded (LBHB) diad His 57-Asp 102 and the 1H NMR chemical shift of the LBHB proton in tetrahedral, hemiketal complexes of chymotrypsin with peptidyl trifluoromethyl ketones (peptidyl-TFKs ...
Jing Lin, C. Cassidy, Perry A. Frey
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The basicity of His 57-Nepsilon2 within the low-barrier hydrogen-bonded (LBHB) diad His 57-Asp 102 and the 1H NMR chemical shift of the LBHB proton in tetrahedral, hemiketal complexes of chymotrypsin with peptidyl trifluoromethyl ketones (peptidyl-TFKs ...
Jing Lin, C. Cassidy, Perry A. Frey
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The low-barrier hydrogen bond in enzymic catalysis
2010Publisher Summary This chapter describes the various aspects of the low-barrier hydrogen bond in enzymic catalysis. Hydrogen bonds come in a continuum of bond lengths and strengths. The first examples of enzymatic reactions where low-barrier hydrogen bonds played a role involved enolization of the substrate to change the p K of a key group in the ...
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, 1997
It has been customary to accept that the observation of a highly deshielded proton is conclusive evidence that the molecule possesses a so-called low-barrier hydrogen bond (LBHB).
M. Garcia-Viloca +4 more
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It has been customary to accept that the observation of a highly deshielded proton is conclusive evidence that the molecule possesses a so-called low-barrier hydrogen bond (LBHB).
M. Garcia-Viloca +4 more
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On the Possibility of Using UV Spectroscopy as a Measure of the Low-Barrier Hydrogen Bond
Structural Chemistry, 2003In many enzyme-catalyzed biochemical pathways, a short, strong hydrogen bond between an enzyme and substrate is an important structural feature. These bonds are termed low-barrier hydrogen bonds. In this paper, we show that UV spectra can be used as an experimental technique to determine if a system contains a low-barrier hydrogen bond (LBHB).
Jeffrey E. Miller +3 more
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, 1997
Theoretical calculations in the gas phase on a series of intermolecular complexes formed between 1-methylimidazole (1-MeIm) and four carboxylic acids R−COOH, where R = CF3, CHCl2, C(CH3)Cl2, and CH2Cl, have been carried out.
M. Garcia-Viloca +2 more
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Theoretical calculations in the gas phase on a series of intermolecular complexes formed between 1-methylimidazole (1-MeIm) and four carboxylic acids R−COOH, where R = CF3, CHCl2, C(CH3)Cl2, and CH2Cl, have been carried out.
M. Garcia-Viloca +2 more
semanticscholar +1 more source
Biochemistry, 1996
The N delta 1 proton of His 64 forms a hydrogen bond with Asp 32, as part of the catalytic triad in serine proteases of the subtilisin family. His 64 in subtilisin has been studied by 1H and 15N NMR spectroscopy in the presence and absence of peptidyl ...
C. J. Halkides +2 more
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The N delta 1 proton of His 64 forms a hydrogen bond with Asp 32, as part of the catalytic triad in serine proteases of the subtilisin family. His 64 in subtilisin has been studied by 1H and 15N NMR spectroscopy in the presence and absence of peptidyl ...
C. J. Halkides +2 more
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Unraveling Low‐Barrier Hydrogen Bonds in Complex Systems with a Simple Quantum Topological Criterion
Chemistry – A European Journal, 2011The importance of low-barrier hydrogen bonds (LBHBs) in enzyme catalysis has remained a controversial topic. LBHBs are defined as protons that are delocalized between two heavy atoms. Since the 1990s LBHBs have been proposed to play a crucial role in several enzyme-catalytic pathways by stabilizing transition states or reaction intermediates.
Chaudret, Robin +3 more
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Characterization of a low barrier hydrogen bond in the active site of chymotrypsin
Journal of Molecular Structure, 2002Abstract The possibility of strong hydrogen bonding in aqueous solutions is supported by spectroscopic and chemical properties of proton sponges and internally strained dicarboxylic acid monoanions in aqueous and aqueous/acetone solutions. A species of low barrier hydrogen bond (LBHB) in aqueous solutions is the downfield proton in transition state ...
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