Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Studies in vitro on the involvement of O-sulphate esters in the formation of O-methylated 3,4-dihydroxybenzoic acid by rat liver.

ABSTRACT: The involvement of O-sulphate esters in the directed O-methylation was investigated in vitro with a dialysed "high-speed' supernatant from rat liver as the enzyme preparation and the catechol compound 3,4-dihydroxybenzoic acid as the substrate. The enzyme reactions involved were studied separately with the O-methylated and O-sulphated derivatives. The rate of hydrolysis by arylsulphatase was 14.5 nmol/min per mg of protein for 3-methoxy-4-sulphonyloxybenzoic acid and 10.1 nmol/min per mg of protein for 4-methoxy-3-sulphonyloxybenzoic acid. The sulphotransferase activity towards the guaiacols 4-hydroxy-3-methoxybenzoic acid and 3-hydroxy-4-methoxybenzoic acid was 570pmol of 4-O-sulphated and 350pmol of 3-O-sulphated product formed/min per mg of protein. The 3-O- and 4-O-sulphate esters of 3,4-dihydroxybenzoic acid could not serve as substrates for the catechol O-methyltransferase reaction. When either ester was incubated in the presence of S-adenosyl-L-methionine, but without the arylsulphatase inhibitor KH2PO4, 3,4-dihydroxybenzoic acid was formed, which was subsequently O-methylated in a meta/para ratio of 4.6. It is concluded that O-methylation can precede O-sulphation but that O-sulphation prevents further metabolism by O-methylation. Also O-sulphate esters do not have a directing effect on O-methylation. From the study of the simultaneous action of sulphotransferase and catechol O-methyltransferase on 3,4-dihydroxybenzoic acid we conclude that O-sulphation and O-methylation proceed independently of each other under the assay conditions used, both directed preferentially to the 3-hydroxy group.

SUBMITTER: Pennings EJ

PROVIDER: S-EPMC1162679 | biostudies-other | 1981 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Studies on the meta and para O-sulphation of the catechol compound 3,4-dihydroxybenzoic acid by rat liver sulphotransferase in vitro.

Project description:The enzymic meta and para O-sulphation of 3,4-dihydroxybenzoic acid was investigated in vitro with a dialysed high-speed supernatant from rat liver. The O-sulphated products were identified by comparison with the reference compounds. The chemical synthesis and identification of the reference O-sulphate esters is described in detail. The sulphotransferase activity of the dialysed supernatant from rat liver towards 3,4-dihydroxybenzoic acid was 580 pmol of 3-O-sulphate and 120 pmol of 4-O-sulphate formed/min per mg of protein at the optimal pH of 7.4. The meta/para ratio of O-sulphation was independent of pH, time of incubation, concentration of enzyme and presence of dithiothreitol. The O-sulphate esters of 3,4-dihydroxybenzoic acid were found to be good substrates for the arylsulphatase reaction at pH 5.6. The arylsulphatase activity of a dialysed preparation from rat liver was 4.0 nmol of 3-O- and 5.7 nmol of 4-O-sulphate ester hydrolysed/min per mg of protein, respectively. Arylsulphatase from Helix pomatia had an activity of 620 pmol of 3-O-sulphate and of 16.6 nmol of 4-O-sulphate ester hydrolysed/min per unit (mumol/h) of sulphatase.

| S-EPMC1162190 | biostudies-other

Synthesis of Furandicarboxylic Acid Esters From Nonfood Feedstocks Without Concomitant Levulinic Acid Formation.

Project description:5-Hydroxymethylfurfural (HMF) is a versatile intermediate in biomass conversion pathways. However, the notoriously unstable nature of HMF imposes challenges to design selective routes to chemicals such as furan-2,5-dicarboxylic acid (FDCA). Here, a new strategy for obtaining furans is presented, bypassing the formation of the unstable HMF. Instead of starting with glucose/fructose and thus forming HMF as an intermediate, the new route starts from uronic acids, which are abundantly present in many agro residues such as sugar beet pulp, potato pulp, and citrus peels. Conversion of uronic acids, via ketoaldonic acids, to the intermediate formylfuroic acid (FFA) esters, and subsequently to FDCA esters, proceeds without formation of levulinic acid or insoluble humins. This new route provides an attractive strategy to valorize agricultural waste streams and a route to furanic building blocks without the co-production of levulinic acid or humins.

| S-EPMC5413837 | biostudies-literature

Stereoselective formation of trisubstituted vinyl boronate esters by the acid-mediated elimination of α-hydroxyboronate esters.

Project description:The copper-catalyzed diboration of ketones followed by an acid-catalyzed elimination leads to the formation of 1,1-disubstituted and trisubstituted vinyl boronate esters with moderate to good yields and selectivity. Addition of tosic acid to the crude diboration products provides the corresponding vinyl boronate esters upon elimination. The trisubstituted vinyl boronate esters are formed as the (Z)-olefin isomer, which was established by subjecting the products to a Suzuki-Miyaura coupling reaction to obtain alkenes of known geometry.

| S-EPMC4120978 | biostudies-literature

Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase.

Project description:Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.

| S-EPMC1185802 | biostudies-other

Novel Galactopyranoside Esters: Synthesis, Mechanism, In Vitro Antimicrobial Evaluation and Molecular Docking Studies.

Project description:One-step direct unimolar valeroylation of methyl α-D-galactopyranoside (MDG) mainly furnished the corresponding 6-O-valeroate. However, DMAP catalyzed a similar reaction that produced 2,6-di-O-valeroate and 6-O-valeroate, with the reactivity sequence as 6-OH > 2-OH > 3-OH,4-OH. To obtain novel antimicrobial agents, 6-O- and 2,6-di-O-valeroate were converted into several 2,3,4-tri-O- and 3,4-di-O-acyl esters, respectively, with other acylating agents in good yields. The PASS activity spectra along with in vitro antimicrobial evaluation clearly indicated that these MDG esters had better antifungal activities than antibacterial agents. To rationalize higher antifungal potentiality, molecular docking was conducted with sterol 14α-demethylase (PDB ID: 4UYL, Aspergillus fumigatus), which clearly supported the in vitro antifungal results. In particular, MDG ester 7-12 showed higher binding energy than the antifungal drug, fluconazole. Additionally, these compounds were found to have more promising binding energy with the SARS-CoV-2 main protease (6LU7) than tetracycline, fluconazole, and native inhibitor N3. Detailed investigation of Ki values, absorption, distribution, metabolism, excretion, and toxicity (ADMET), and the drug-likeness profile indicated that most of these compounds satisfy the drug-likeness evaluation, bioavailability, and safety tests, and hence, these synthetic novel MDG esters could be new antifungal and antiviral drugs.

| S-EPMC9268324 | biostudies-literature

In vitro inhibition of glutathione-S-transferase by dopamine and its metabolites, 3,4-dihydroxyphenylacetaldehyde and 3,4-dihydroxyphenylacetic acid.

Project description:Parkinson's disease is characterized by dopamine dyshomeostasis and oxidative stress. The aldehyde metabolite of dopamine, 3,4-dihydroxyphenylacetaldehyde (DOPAL), has been reported to be cytotoxic and capable of protein modification. Protein modification by DOPAL has been implicated in the pathogenesis of Parkinson's disease, but the complete pathology is unknown. Our findings show that DOPAL modifies glutathione S-transferase (GST), an important enzyme in the antioxidant defense system. DOPAL, dopamine, and the metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), inhibited the activity of GST isolated from N27 dopaminergic cells at an IC50 of 31.46 μM, 82.32 μM, and 260.0 μM, respectively. DOPAL, dopamine, and DOPAC inhibited commercially available equine liver GST at an IC50 of 23.72 μM, 32.17 μM, and 73.70 μM, respectively. This inhibition was time dependent and irreversible. 1 mM ʟ-cysteine or glutathione fully protected GST activity from DOPAL, DA, and DOPAC inhibition. 1 mM carnosine partially protected GST activity from DA inhibition. Furthermore, ʟ-cysteine was found to protect GST by forming a putative thiazolidine conjugate with DOPAL. We conclude that GST inactivation may be a part of the broader etiopathology of Parkinson's disease.

| S-EPMC8440459 | biostudies-literature

Medium chain unsaturated fatty acid ethyl esters inhibit persister formation of Escherichia coli via antitoxin HipB

Project description:Persisters represent a small bacterial population that is dormant and that survives under antibiotic treatment without experiencing genetic adaptation. Persisters are also considered one of the major reasons for recalcitrant chronic bacterial infections. Although several mechanisms of persister formation have been proposed, it is not clear how cells enter the dormant state in the presence of antibiotics or how persister cell formation can be effectively controlled. A fatty acid compound, cis-2-decenoic acid, was reported to decrease persister formation as well as revert the dormant cells to a metabolically active state. We reasoned that some fatty acid compounds may be effective in controlling bacterial persistence because they are known to benefit host immune systems. This study investigated persister cell formation by pathogens that were exposed to nine fatty acid compounds during antibiotic treatment. We found that three medium chain unsaturated fatty acid ethyl esters (ethyl trans-2-decenoate, ethyl trans-2-octenoate, and ethyl cis-4-decenoate) decreased the level of Escherichia coli persister formation up to 110-fold when cells were exposed to ciprofloxacin or ampicillin antibiotics. RNA sequencing analysis and gene deletion persister studies elucidated that these fatty acids inhibit bacterial persistence by regulating antitoxin HipB. A similar persister cell reduction was observed for pathogenic E. coli EDL933, Pseudomonas aeruginosa PAO1, and Serratia marcescens ICU2-4 strains. This study demonstrates that fatty acid ethyl esters can be used to disrupt bacterial dormancy to combat persistent infectious diseases.

2018-08-08 | GSE112545 | GEO

Targeted Synthesis of 3,3'-, 3,4'- and 3,6'-Phenylpropanoid Sucrose Esters.

Project description:In this study, we report on an orthogonal strategy for the precise synthesis of 3,3'-, 3,4'-, and 3,6'-phenylpropanoid sucrose esters (PSEs). The strategy relies on carefully selected protecting groups and deprotecting agents, taking into consideration the reactivity of the four free hydroxyl groups of the key starting material: di-isopropylidene sucrose 2. The synthetic strategy is general, and potentially applies to the preparation of many natural and unnatural PSEs, especially those substituted at 3-, 3'-, 4'- and 6'-positions of PSEs.

| S-EPMC8780461 | biostudies-literature

The reaction of aralkyl sulphate esters with glutathione catalysed by rat liver preparations.

Project description:1. Rat liver supernatant preparations catalyse the reactions of some aralkyl sulphate esters with GSH to yield S-aralkylglutathione derivatives. 2. A glutathione S-transferase that catalyses these reactions has been purified 16-fold. 3. The purified enzyme preparation catalyses the release of sulphate ions from benzyl sulphate, 1-menaphthyl (naphth-1-ylmethyl) sulphate and phenanthr-9-ylmethyl sulphate only in the presence of GSH. It does not cause the release of sulphate ions from prop-1-yl sulphate, l-serine O-sulphate, phenyl sulphate or oestrone 3-sulphate even when GSH is added. 4. The stability and specificity of the enzyme and its response to inhibitors and to changes of pH were studied. 5. The activity of the preparation was compared with the activities of glutathione S-transferases described previously.

| S-EPMC1176644 | biostudies-other

A preparation of murine liver fragments for in vitro studies: liver preparation for toxicological studies.

Project description:BackgroundThe aim of this study was to develop liver tissue preparation suitable for investigating toxins. Hepatocyte respiration, ATP content, urea synthesis, caspase activity and morphology were measured as a function of in vitro incubation time. Mice were anesthetized by sevoflurane inhalation. Small liver fragments were then rapidly excised and incubated at 37°C in Krebs-Henseleit buffer (continuously gassed with 95% O2: 5% CO2) for up to 6 h. Phosphorescence O2 analyzer was used to determine the rate of cellular mitochondrial O2 consumption (kc, μM O2 min-1 mg-1). Cellular ATP was measured using the luciferin/luciferase system. The caspase-3 substrate N-acetyl-asp-glu-val-asp-7-amino-4-methylcoumarin (Ac-DEVD-AMC) was used to monitor intracellular caspase activity; cleaved AMC moieties (reflecting caspase activity) were separated on HPLC and detected by fluorescence.FindingsRespiration was inhibited by cyanide, confirming the oxidation occurred in the respiratory chain. The values of kc (mean ± SD) for 0≤ t ≤6 h were 0.15 ± 0.02 μM O2 min-1 mg-1 (n = 18, coefficient of variation, CV = 13%), ATP content 131 ± 69 pmol mg-1 (1≤ t ≤6 h, n = 16, CV = 53%), synthesized urea 0.134 ± 0.017 mg/dL mg-1 in 50 min (0≤ t ≤6 h, n = 14, CV = 13%), and AMC peak area 62,540 ± 26,227 arbitrary units mg-1 (1≤ t ≤6 h, n = 3, CV = 42%). Hepatocyte morphology and organelles were reasonably persevered.ConclusionsThe described liver tissue preparation demonstrates stable hepatocyte structure, ultrastructure and biomarkers for up to 6 h, permitting in vitro studies.

| S-EPMC3598918 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data