Results 261 to 270 of about 136,042 (297)

Subangstrom crystallography reveals that short ionic hydrogen bonds, and not a His-Asp low-barrier hydrogen bond, stabilize the transition state in serine protease catalysis.

Journal of the American Chemical Society, 2006
To address questions regarding the mechanism of serine protease catalysis, we have solved two X-ray crystal structures of alpha-lytic protease (alphaLP) that mimic aspects of the transition states: alphaLP at pH 5 (0.82 A resolution) and alphaLP bound to
C. Fuhrmann, M. Daugherty, D. Agard
semanticscholar   +1 more source

On the Possibility of Detecting Low Barrier Hydrogen Bonds with Kinetic Measurements

Journal of Chemical Information and Computer Sciences, 2003
Recent 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
Michael Messina, Jeffrey E. Miller, Christopher J. Halkides, Nolan E. Dean   +3 more
openaire   +3 more sources

The crucial role of water in shaping low-barrier hydrogen bonds

Physical Chemistry Chemical Physics, 2016
Low-barrier hydrogen bonds (LBHBs) are key components in a range of chemical processes, often appearing in metal-mediated catalytic applications.
Timothy M. Korter, Michael T. Ruggiero
openaire   +3 more sources

Follow the protons: a low-barrier hydrogen bond unifies the mechanisms of the aspartic proteases.

Accounts of Chemical Research, 2001
Seven proton transfers in five steps participate in a catalytic turnover of an aspartic protease. The Rosetta Stone for elucidating their role is a low-barrier hydrogen bond that holds the two aspartic carboxyls in a coplanar conformation.
D. Northrop
semanticscholar   +1 more source

A low-barrier hydrogen bond in the catalytic triad of serine proteases? Theory versus experiment.

Science, 1997
Cleland and Kreevoy recently advanced the idea that a special type of hydrogen bond (H-bond), termed a low-barrier hydrogen bond (LBHB), may account for the "missing" transition state stabilization underlying the catalytic power of many enzymes, and Frey
Elissa L. Ash, J. Sudmeier, E. Fabo, W. Bachovchin   +3 more
semanticscholar   +1 more source

Combined high-resolution neutron and X-ray analysis of inhibited elastase confirms the active-site oxyanion hole but rules against a low-barrier hydrogen bond.

Journal of the American Chemical Society, 2009
To help resolve long-standing questions regarding the catalytic activity of the serine proteases, the structure of porcine pancreatic elastase has been analyzed by high-resolution neutron and X-ray crystallography.
T. Tamada, T. Kinoshita, K. Kurihara, M. Adachi, T. Ohhara, K. Imai, R. Kuroki, T. Tada   +7 more
semanticscholar   +1 more source

Are Short, Low-Barrier Hydrogen Bonds Unusually Strong?

Accounts of Chemical Research, 2010
In a symmetric hydrogen bond (H-bond), the hydrogen atom is perfectly centered between the two donor atoms. The energy diagram for hydrogen motion is thus a single-well potential, rather than the double-well potential of a more typical H-bond, in which the hydrogen is covalently bonded to one atom and H-bonded to the other.
openaire   +3 more sources

Evidence of a Low-Barrier Hydrogen Bond in the Tryptophan Synthase Catalytic Mechanism

Biochemistry, 1996
In the absence of other substrates, L-Ser reacts rapidly with the tryptophan synthase alpha 2 beta 2 bienzyme from Salmonella typhimurium at pH 7.8 and 25 degrees C to give an equilibrating mixture of species dominated by comparable amounts of the L-Ser external aldimine Schiff base, E(Aex1), and the alpha-aminoacrylate Schiff base, E(A-A).
Michael F. Dunn, Catherine A. Leja, Oscar Hur   +2 more
openaire   +3 more sources

Low-barrier hydrogen bond hypothesis in the catalytic triad residue of serine proteases: correlation between structural rearrangement and chemical shifts in the acylation process.

Biochemistry, 2006
To elucidate the catalytic advantage of the low-barrier hydrogen bond (LBHB), we analyze the hydrogen bonding network of the catalytic triad (His57-Asp102-Ser195) of serine protease trypsin, one of the best examples of the LBHB reaction mechanism ...
Toyokazu Ishida
semanticscholar   +1 more source

Low barrier hydrogen bonds in sterically modified Schiff bases

Journal of the Chemical Society, Perkin Transactions 2, 2002
Five derivatives of an ortho-hydroxy Schiff base (2-(N-alkyl-α-iminoethyl)phenols) with very short intramolecular hydrogen bonds (dO(H)⋯N ≤ 2.500 A) were synthesised. The crystal structures were determined. The steric repulsion of the substituted methyl group results in an unusual strengthening of the hydrogen bonds, decreasing the barrier for the ...
Aleksander Koll, Tadeusz Głowiak, Aleksander Filarowski   +2 more
openaire   +2 more sources