scholarly journals NMR studies of the hydrogen bonds involving the catalytic triad of Escherichia coli thioesterase/protease I

FEBS Letters ◽  
2002 ◽  
Vol 528 (1-3) ◽  
pp. 203-206 ◽  
Author(s):  
Sergiy I Tyukhtenko ◽  
Alexandra V Litvinchuk ◽  
Chi-Fon Chang ◽  
Ruey-Jyh Leu ◽  
Jei-Fu Shaw ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Bonds ◽  
Catalytic Triad ◽  
Nmr Studies

Selectively Labeling the Heterologous Protein in Escherichia coli for NMR Studies: A Strategy to Speed Up NMR Spectroscopy

2001 ◽  
Vol 148 (1) ◽  
pp. 142-146 ◽  
Author(s):  
F.C.L. Almeida ◽  
G.C. Amorim ◽  
V.H. Moreau ◽  
V.O. Sousa ◽  
A.T. Creazola ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nmr Spectroscopy ◽  
Heterologous Protein ◽  
Nmr Studies ◽  
Speed Up

Preliminary NMR studies of Thermus thermophilus ribosomal protein S19 overproduced in Escherichia coli

FEBS Letters ◽  
1997 ◽  
Vol 415 (2) ◽  
pp. 155-159 ◽  
Author(s):  
Natalia L Davydova ◽  
Alexey V Rak ◽  
Olga I Gryaznova ◽  
Anders Liljas ◽  
Bengt-Harald Jonsson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Protein ◽  
Thermus Thermophilus ◽  
Nmr Studies ◽  
Ribosomal Protein S19

The syntheses of 6-C-alkyl derivatives of methyl α-isomaltoside for a study of the mechanism of hydrolysis by amyloglucosidase

2001 ◽  
Vol 79 (2) ◽  
pp. 238-255 ◽  
Author(s):  
Ulrike Spohr ◽  
Nghia Le ◽  
Chang-Chun Ling ◽  
Raymond U Lemieux
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Model ◽  
Aromatic Amino Acids ◽  
Hydroxyl Group ◽  
Bulk Solution ◽  
Anomeric Effect ◽  
Nmr Studies ◽  
Intermolecular Hydrogen Bonds ◽  
Model Calculations ◽  
Derivatives Of

The epimeric (6aR)- and (6aS)-C-alkyl (methyl, ethyl and isopropyl) derivatives of methyl α-isomaltoside (1) were synthesized in order to examine the effects of introducing alkyl groups of increasing bulk on the rate of catalysis for the hydrolysis of the interunit α-glycosidic bond by the enzyme amyloglucosidase, EC 3.2.1.3, commonly termed glucoamylase (AMG). It was previously established that methyl (6aR)-C-methyl α-isomaltoside is hydrolysed about 2 times faster than methyl α-isomaltoside and about 8 times faster than its S-isomer. The kinetics for the hydrolyses of the ethyl and isopropyl analogs were also recently published. As was expected from molecular model calculations, all the R-epimers are good substrates. A rationale is presented for the catalysis based on conventional mechanistic theories that includes the assistance for the decomposition of the activated complex to products by the presence of a hydrogen bond, which connects the 4a-hydroxyl group to the tryptophane and arginine units. It is proposed that activation of the initially formed complex to the transition state is assisted by the energy released as a result of both of the displacement of perturbed water molecules of hydration at the surfaces of both the polyamphiphilic substrate and the combining site and the establishment of intermolecular hydrogen bonds, i.e., micro-thermodynamics. The dissipation of the heat to the bulk solution is impeded by a shell of aromatic amino acids that surround the combining site. Such shields are known to be located around the combining sites of lectins and carbohydrate specific antibodies and are considered necessary to prevent the disruption of the intermolecular hydrogen bonds, which are of key importance for the stability of the complex. These features together with the exquisite stereoelectronic dispositions of the reacting molecules within the combining site offer a rationalization for the catalysis at ambient temperatures and near neutral pH. The syntheses involved the addition of alkyl Grignard reagents to methyl 6-aldehydo-α-D-glucopyranoside. The addition favoured formation of the S-epimers by over 90%. Useful amounts of the active R-isomers were obtained by epimerization of the chiral centers using conventional methods. Glycosylation of the resulting alcohols under conditions for bromide-ion catalysis, provided methyl (6aS)- and (6aR)-C-alkyl-hepta-O-benzyl-α-isomaltosides. Catalytic hydrogenolysis of the benzyl groups afforded the desired disaccharides. 1H NMR studies established the absolute configurations and provided evidence for conformational preferences.Key words: amyloglucosidase (AMG), exo-anomeric effect, 6-C-alkyl-α-D-glucopyranosides and isomaltosides, mechanism of enzyme catalysis.

scholarly journals An Efficient System for Intestinal On-site Butyrate Production Using Novel Microbiome-Derived Esterases

2021 ◽  
Author(s):  
Dah Hyun Jung ◽  
Ji Hyun Yong ◽  
Wontae Hwang ◽  
Mi Young Yoon ◽  
Sang Sun Yoon
Keyword(s):  
Escherichia Coli ◽  
Artificial Chromosome ◽  
Short Chain Fatty Acids ◽  
Catalytic Triad ◽  
Nucleotide Sequence Analysis ◽  
Efficient System ◽  
Gastrointestinal Health ◽  
Metagenome Library ◽  
The Family ◽  
Butyrate Production

Abstract Short-chain fatty acids, especially butyrate, play beneficial roles in sustaining gastrointestinal health. However, due to limitations associated with direct consumption of butyrate, there has been interest in using prodrugs of butyrate. Tributyrin (TB), a triglyceride composed of three butyrate molecules and a glycerol, is a well-studied precursor of butyrate. We screened a metagenome library consisting of 5,760 bacterial artificial chromosome clones, with DNA inserts originating from mouse microbiomes, and identified two clones that efficiently hydrolyse TB into butyrate. Nucleotide sequence analysis indicated that inserts in these two clones are derived from unknown microbes. BLASTp analysis, however, revealed that each insert contains a gene homologous to acetylesterase or esterase genes, from Clostridium spp. and Bacteroides spp., respectively. Predicted structures of these two proteins both contain serine-histidine-aspartate catalytic triad, highly conserved in the family of esterases. Escherichia coli host expressing each of the two candidate genes invariably produced greater amounts of butyrate in the presence of TB. Importantly, administration of TB together with cloned Escherichia coli cells alleviated inflammatory symptoms in a mouse model of acute colitis. Based on these results, we established an efficient on-site and real-time butyrate production system that releases butyrate in a controlled manner inside the intestine

NMR Studies of Solid Pentachlorophenol-4-Methylpyridine Complexes Exhibiting Strong OHN Hydrogen Bonds: Geometric H/D Isotope Effects and Hydrogen Bond Coupling Cause Isotopic Polymorphism

2012 ◽  
Vol 116 (46) ◽  
pp. 11370-11387 ◽  
Author(s):  
Brenda C. K. Ip ◽  
Ilya G. Shenderovich ◽  
Peter M. Tolstoy ◽  
Jaroslaw Frydel ◽  
Gleb S. Denisov ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Isotope Effects ◽  
Nmr Studies
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