Results 251 to 260 of about 10,014,931 (288)
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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 ...
Perry A Frey
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Journal of the American Chemical Society, 1997
Relative strengths of normal and low-barrier hydrogen bonds (LBHBs) in the gas phase were analyzed by means of quantum-mechanical and thermodynamic calculations on the mesaconic/citraconic and several maleic/fumaric cis/trans isomerization equilibria. All geometries were fully optimized with correlation effects included via second-order Moller−Plesset ...
Mireia Garcia Viloca +2 more
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Relative strengths of normal and low-barrier hydrogen bonds (LBHBs) in the gas phase were analyzed by means of quantum-mechanical and thermodynamic calculations on the mesaconic/citraconic and several maleic/fumaric cis/trans isomerization equilibria. All geometries were fully optimized with correlation effects included via second-order Moller−Plesset ...
Mireia Garcia Viloca +2 more
exaly +2 more sources
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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Absorption Wavelength Along Chromophore Low-Barrier Hydrogen Bonds
SSRN Electronic Journal, 2021In low-barrier hydrogen bonds (H-bonds), the pKa values for the H-bond donor and acceptor moieties are nearly equal, whereas the redox potential values depend on the H+ position. Spectroscopic details of low-barrier H-bonds remain unclear. Here, we report the absorption wavelength along low-barrier H-bonds in protein environments, using a quantum ...
Masaki Tsujimura +2 more
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Strong, Low-Barrier Hydrogen Bonds May Be Available to Enzymes
Biochemistry, 2014The debate over the possible role of strong, low-barrier hydrogen bonds in stabilizing reaction intermediates at enzyme active sites has taken place in the absence of an awareness of the upper limits to the strengths of low-barrier hydrogen bonds involving amino acid side chains. Hydrogen bonds exhibit their maximal strengths in isolation, i.e., in the
Jacob D, Graham +4 more
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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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