Imidazole catalyses in aqueous systems. V. Enzyme-like catalysis in the hydrolysis of a phenyl ester by copolymers containing a benzimidazole group. Rate acceleration by bound phenols and the mode of side chain aggregation in polymer catalysts

1971 ◽  
Vol 93 (17) ◽  
pp. 4247-4255 ◽  
Author(s):  
Toyoki Kunitake ◽  
Seiji Shinkai
Keyword(s):  
Side Chain ◽  
Aqueous Systems ◽  
Phenyl Ester ◽  
Rate Acceleration ◽  
Group Rate ◽  
Hydrolysis Of ◽  
Benzimidazole Group

Synthesis of Normuramic Acid Carba Analog and Its Glycopeptide Derivative Resistant to β-Elimination Splitting of the Side Chain

2000 ◽  
Vol 65 (11) ◽  
pp. 1726-1736 ◽  
Author(s):  
Miroslav Ledvina ◽  
Radka Pavelová ◽  
Anna Rohlenová ◽  
Jan Ježek ◽  
David Šaman
Keyword(s):  
Ethyl Ester ◽  
Alkaline Hydrolysis ◽  
Benzyl Ester ◽  
Side Chain ◽  
Propanoic Acid ◽  
Hydrolysis Of

Carba analogs of normuramic acid, i.e., 3-(benzyl 2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-3-yl)propanoic acid derivatives (nitrile or esters) 3a-3c were prepared by addition of radicals generated from benzyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-3-O-[(methylsulfanyl)thiocarbonyl]- (2a) or -3-O-(phenoxythiocarbonyl)-α-D-glucopyranoside (2b) with Bu3SnH to acrylonitrile or acryl esters. Alkaline hydrolysis of ethyl ester 3c afforded 3-(benzyl 2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-3-yl)propanoic acid (5). Coupling of acid 5 with L-2-aminobutanoyl-D-isoglutamine benzyl ester trifluoroacetate and subsequent deprotection of the intermediate 6 furnished N-[3-(2-acetamido-2,3-dideoxy-α-D-glucopyranosid-3-yl)propanoyl]-L-2-aminobutanoyl-D-isoglutamine (7).

scholarly journals “Newton’s cradle” proton relay with amide–imidic acid tautomerization in inverting cellulase visualized by neutron crystallography

2015 ◽  
Vol 1 (7) ◽  
pp. e1500263 ◽  
Author(s):  
Akihiko Nakamura ◽  
Takuya Ishida ◽  
Katsuhiro Kusaka ◽  
Taro Yamada ◽  
Shinya Fushinobu ◽  
...  
Keyword(s):  
Glycoside Hydrolases ◽  
Side Chain ◽  
Enzymatic Reactions ◽  
X Ray Diffraction ◽  
Peptide Bonds ◽  
Proton Relay ◽  
Newton’S Cradle ◽  
Dynamics Simulations ◽  
Hydrolysis Of

Hydrolysis of carbohydrates is a major bioreaction in nature, catalyzed by glycoside hydrolases (GHs). We used neutron diffraction and high-resolution x-ray diffraction analyses to investigate the hydrogen bond network in inverting cellulase PcCel45A, which is an endoglucanase belonging to subfamily C of GH family 45, isolated from the basidiomycete Phanerochaete chrysosporium. Examination of the enzyme and enzyme-ligand structures indicates a key role of multiple tautomerizations of asparagine residues and peptide bonds, which are finally connected to the other catalytic residue via typical side-chain hydrogen bonds, in forming the “Newton’s cradle”–like proton relay pathway of the catalytic cycle. Amide–imidic acid tautomerization of asparagine has not been taken into account in recent molecular dynamics simulations of not only cellulases but also general enzyme catalysis, and it may be necessary to reconsider our interpretation of many enzymatic reactions.

Hydrolysis of Zinc Ion and Solubility of Zinc Oxide in High-Temperature Aqueous Systems

1997 ◽  
Vol 127 (3) ◽  
pp. 292-299 ◽  
Author(s):  
Yukiko Hanzawa ◽  
Daisuke Hiroishi ◽  
Chihiro Matsuura ◽  
Kenkichi Ishigure ◽  
Masashi Nagao ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
High Temperature ◽  
Zinc Ion ◽  
Aqueous Systems ◽  
Hydrolysis Of

scholarly journals Photodegradation and Hydrolysis of Chlorpyrifos in Aqueous Systems

2014 ◽  
Vol 33 (4) ◽  
pp. 553 ◽  
Author(s):  
JE Ukpebor ◽  
S Ikpeni ◽  
NC Ejiogu ◽  
EE Ukpebor
Keyword(s):  
Aqueous Systems ◽  
Hydrolysis Of

SUBSTITUTION AT OCTAHEDRAL CENTERS: II. EFFECT OF SALTS UPON THE RATE OF HYDROLYSIS OF THE HALOPENTAMMINECHROMIUM(III) IONS

1961 ◽  
Vol 39 (11) ◽  
pp. 2371-2379 ◽  
Author(s):  
T. P. Jones ◽  
W. E. Harris ◽  
W. J. Wallace
Keyword(s):  
Charge Transfer ◽  
Transfer Effect ◽  
Ion Pair ◽  
Pair Formation ◽  
Sodium Salts ◽  
Rate Acceleration ◽  
Rate Of Hydrolysis ◽  
A Charge ◽  
Hydrolysis Of ◽  
Octahedral Configuration

A study of the hydrolysis of the halopentamminechromium(III) ions in the presence of the sodium salts of weak acids reveals a rate acceleration due to specific ion-pair formation. The acceleration is due partly to a charge-transfer effect and partly to the fact that the ion helps to maintain the octahedral configuration of the complex in the transition state. It is concluded that the reaction occurs by dissociation, but without collapse of the structure to a five-co-ordinated intermediate.

scholarly journals Structure of a Talaromyces pinophilus GH62 arabinofuranosidase in complex with AraDNJ at 1.25 Å resolution

2018 ◽  
Vol 74 (8) ◽  
pp. 490-495 ◽  
Author(s):  
Olga V. Moroz ◽  
Lukasz F. Sobala ◽  
Elena Blagova ◽  
Travis Coyle ◽  
Wei Peng ◽  
...  
Keyword(s):  
Plant Biomass ◽  
Cellulosic Biomass ◽  
Structural Basis ◽  
Side Chain ◽  
Polymeric Substrates ◽  
Hydrolysis Of ◽  
Insight Into ◽  
Positively Charged ◽  
Talaromyces Pinophilus ◽  
Resolution Structure

The enzymatic hydrolysis of complex plant biomass is a major societal goal of the 21st century in order to deliver renewable energy from nonpetroleum and nonfood sources. One of the major problems in many industrial processes, including the production of second-generation biofuels from lignocellulose, is the presence of `hemicelluloses' such as xylans which block access to the cellulosic biomass. Xylans, with a polymeric β-1,4-xylose backbone, are frequently decorated with acetyl, glucuronyl and arabinofuranosyl `side-chain' substituents, all of which need to be removed for complete degradation of the xylan. As such, there is interest in side-chain-cleaving enzymes and their action on polymeric substrates. Here, the 1.25 Å resolution structure of the Talaromyces pinophilus arabinofuranosidase in complex with the inhibitor AraDNJ, which binds with a K d of 24 ± 0.4 µM, is reported. Positively charged iminosugars are generally considered to be potent inhibitors of retaining glycosidases by virtue of their ability to interact with both acid/base and nucleophilic carboxylates. Here, AraDNJ shows good inhibition of an inverting enzyme, allowing further insight into the structural basis for arabinoxylan recognition and degradation.

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