Results 241 to 250 of about 207,343 (281)
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The strength of a low-barrier hydrogen bond in water
Tetrahedron Letters, 2002Abstract There are large differences between the acidity of the enol of the acyclic diketone, 2,4-pentanedione and those of two cyclic diketones, 1,3-cyclopentanedione and 1,3-cyclohexanedione. Computational studies have demonstrated that these differences are largely due to the strength of the internal low-barrier hydrogen bond (LBHB) in the enol of
Freeman M Wong
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Low-barrier hydrogen bonds in proteins
Crystallography Reviews, 2013Hydrogen bonding interactions are one of the most important chemical interactions among materials, especially biological materials, which help confer specificity, which is crucial for their efficient functioning. Recently, low-barrier hydrogen bonds (LBHBs) have been proposed to play a critical role in enzyme catalysis.
Samarth Hegde, R R Choudhury, Amit Das
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A low-barrier hydrogen bond in the catalytic triad of serine proteases
Science, 1994Spectroscopic properties of chymotrypsin and model compounds indicate that a low-barrier hydrogen bond participates in the mechanism of serine protease action. A low-barrier hydrogen bond between Nδ1 of His 57 and the β-carboxyl group of Asp 102 in chymotrypsin can facilitate the formation of
Perry A Frey
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Low-Barrier Hydrogen Bonds and Enzymic Catalysis
Science, 1994Formation of a short (less than 2.5 angstroms), very strong, low-barrier hydrogen bond in the transition state, or in an enzyme-intermediate complex, can be an important contribution to enzymic catalysis. Formation of such a bond can supply 10 to 20 kilocalories per mole and thus facilitate difficult reactions such as enolization of ...
W W, Cleland, M M, Kreevoy
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Journal of the American Chemical Society, 2013
We report quantifying the strengths of different types of hydrogen bonds in hydrogen-bond networks (HBNs) via measurement of the adiabatic electron detachment energy of the conjugate base of a small covalent polyol model compound (i.e., (HOCH2CH2CH(OH)CH2)2CHOH) in the gas phase and the pKa of the corresponding acid in DMSO.
Alireza, Shokri +4 more
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We report quantifying the strengths of different types of hydrogen bonds in hydrogen-bond networks (HBNs) via measurement of the adiabatic electron detachment energy of the conjugate base of a small covalent polyol model compound (i.e., (HOCH2CH2CH(OH)CH2)2CHOH) in the gas phase and the pKa of the corresponding acid in DMSO.
Alireza, Shokri +4 more
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On the Possibility of Detecting Low Barrier Hydrogen Bonds with Kinetic Measurements
Journal of Chemical Information and Computer Sciences, 2003Recent experimental evidence has pointed to the possible presence of a short, strong hydrogen bond in the enzyme-substrate transition states in some biochemical reactions. To date, most experimental measures of these short, strong hydrogen bonds have monitored their equilibrium properties. In this work we show that kinetic measurements can also be used
Nolan E. Dean +3 more
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Turning Low Barrier Hydrogen Bonds on and Off
Journal of the Chinese Chemical Society, 2010AbstractThe hydrogen bond in the [HDihH‐Fda]+ ion (HDih: 4,5‐dihydro‐1H‐imidazole, Fda: 1‐fluoro‐N,N‐dimethylmethaneamine) can be an ordinary single well hydrogen bond (HB) or a low barrier hydrogen bond (LBHB) depending on the orientation of the CH2F group in the Fda molecule.
Timm Lankau, Chin‐Hui Yu
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Science, 1995
Proteins contain mainly weak, conventional hydrogen bonds; however, a few enzymes have low barrier hydrogen bonds (LBHBs) in transition state analog complexes. Hydrogen bonds display variations in physicochemical properties including length, spectroscopic characteristics, and strength.
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Proteins contain mainly weak, conventional hydrogen bonds; however, a few enzymes have low barrier hydrogen bonds (LBHBs) in transition state analog complexes. Hydrogen bonds display variations in physicochemical properties including length, spectroscopic characteristics, and strength.
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Low-Barrier Hydrogen Bonds and Enzymatic Catalysis
Archives of Biochemistry and Biophysics, 2000Short, strong (low barrier) hydrogen bonds occur when the pK values of the atoms sharing the proton are similar. The overall distance is 2.5 A or less, the deuterium fractionation factor is less than 0.5, the proton NMR chemical shift can approach 20 ppm, and deuterium or tritium substitution causes an up-field change in the chemical shift.
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The crucial role of water in shaping low-barrier hydrogen bonds
Physical Chemistry Chemical Physics, 2016Low-barrier hydrogen bonds (LBHBs) are key components in a range of chemical processes, often appearing in metal-mediated catalytic applications.
Michael T, Ruggiero, Timothy M, Korter
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