Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CATECHOL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1987

The oxidation of apomorphine and other catechol compounds by horseradish peroxidase: relevance to the measurement of dihydropteridine reductase activity.

It has been reported by Shen et al. (Shen, R.-S., Smith, R.V., Davis, P.J. and Abell, C.W. (1984) J. Biol. Chem. 259, 8894-9000) that apomorphine and dopamine are potent, non-competitive inhibitors of quinonoid dihydropteridine reductase. In this paper we show that apomorphine, dopamine and other catechol-containing compounds are oxidized rapidly to quinones by the horseradish peroxidase-H2O2 system which is used to generate the quinonoid dihydropterin substrate. These quinones react non-enzymatically with reduced pyridine nucleotides, depleting the other substrate of dihydropteridine reductase. When true initial rates of dihydropteridine reductase-dependent reduction of quinonoid dihydropterins are measured, neither apomorphine nor any other catechol-containing compound that has been tested has been found to inhibit dihydropteridine reductase.

Animals↗
PubMed1989

Nucleotide sequence and expression of the catechol 2,3-dioxygenase-encoding gene of phenol-catabolizing Pseudomonas CF600.

Pseudomonas CF600 degrades phenol and some of its methylated derivatives via a plasmid-encoded catabolic pathway. The catechol 2,3-dioxygenase (C23O) enzyme of this pathway catalyses the conversion of catechol to 2-hydroxymuconic semialdehyde. We have determined the nucleotide (nt) sequence of the dmpB structural gene for this enzyme, and expressed and identified its polypeptide product in Escherichia coli. The xylE gene of TOL plasmid pWWO and the nahH gene of plasmid NAH7 encode analogous C23O enzymes. Comparison of these three genes shows homology of 78-81% on the nt level and 83-87% homology on the amino acid level.

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of a gene coding for the catechol 1,2-dioxygenase of Arthrobacter sp. mA3.

The catA gene, coding for the catechol 1,2-dioxygenase (C12O) of the bacterial strain Arthrobacter sp. mA3, was cloned and expressed in Escherichia coli. One plasmid containing a 6.1-kb EcoRI insert was selected by its ability to degrade catechol and to accumulate cis-cis-muconate. The DNA insert of this plasmid was mapped with restriction enzymes. The catA gene was subcloned on a 1.3-kb PstI-EcoRI fragment by deleting the adjacent restriction fragments. The nucleotide sequence of catA was determined. The C12O is coded for by a gene spanning 849 nucleotides and the deduced M(r) of the protein is 30,560. The polypeptide encoded by the cloned catA gene was expressed in an E. coli minicell system and detected by gel electrophoresis.

Amino Acid Sequence↗
PubMed1994

Cloning of cmpE, a plasmid-borne catechol 2,3-dioxygenase-encoding gene from the aromatic- and chloroaromatic-degrading Pseudomonas sp. HV3.

Pseudomonas sp. strain HV3 degrades aromatics and chloroaromatics. It harbours a mega-plasmid, designated pSKY4, from which the gene cmpE, encoding a catechol 2,3-dioxygenase (C23O) catalyzing the conversion of catechol to 2-hydroxymuconic semialdehyde, was cloned and sequenced. The deduced amino acid (aa) sequence shows the highest homology, 52%, to the deduced aa sequences of xylE1 and dmpB. The deduced 307-aa sequence of cmpE contains the extradiol ring-cleavage signature in the same position as other 307-aa C23O-encoding genes.

Amino Acid Sequence↗
PubMed1993

Simultaneous determination of hydroquinone, catechol and phenol in urine using high-performance liquid chromatography with fluorimetric detection.

A method was developed for simultaneous determination of urinary hydroquinone, catechol and phenol using high-performance liquid chromatography (HPLC) with variable-wavelength fluorimetric detection. Urine samples, after acid hydrolysis, were saturated with sodium sulphate and extracted by diethyl ether. The two buffers used for gradient elution were (A) 10 mM sodium acetate containing 0.5% (v/v) acetic acid and (B) the same as buffer A but containing an additional 20% (v/v) acetonitrile. Hydroquinone, catechol and phenol were separated in a C18 column and detected at 2.9, 6.8 and 13.6 min, respectively. The recovery and reproducibility were generally over 90%. Over 300 extracted samples were analysed and no change in column efficiency was noted. Comparisons were also made with HPLC using ultraviolet (UV) detection and with gas chromatography (GC). The proposed method appears to be more sensitive and reliable than other existing methods. This new method was also validated with urine samples collected from cigarette smokers and from refinery workers exposed to low concentrations of benzene.

Animals↗
PubMed1993

Assay of enzymic O-methylation of catechol oestrogens by high-performance liquid chromatography with coulometric detection.

A simple and sensitive method for the determination of guaiaicol oestrogens enzymatically formed from 2- or 4-hydroxyoestradiol, by means of high-performance liquid chromatography with coulometric detection, has been developed. Catechol and guaiacol oestrogens were efficiently separated on a reversed-phase column, using 0.5% ammonium phosphate buffer (pH 3.0)-acetonitrile (59:41, v/v) as the mobile phase, and detected coulometrically in a screening-oxidation mode at +0.10 V and +0.35 V, respectively. The method was applied to the assay of in vitro enzymic O-methylation of catechol oestrogens. After 2- or 4-hydroxyoestradiol had been incubated with rat red blood cells in the presence of S-adenosylmethionine, the resulting guaiacols and unchanged substrate were percolated through an Extrelut-3 cartridge. The dried eluate was redissolved and directly injected. This simple procedure was as sensitive as the previously reported method using gas chromatography-mass spectrometry in a selected ion monitoring mode.

Animals↗
PubMed1992

Chromosomal mapping of the human catechol-O-methyltransferase gene to 22q11.1----q11.2.

Catechol-O-methyltransferase (COMT; EC 2.1.1.6) is a physiologically important enzyme in the metabolism of catecholamine neurotransmitters and catechol drugs. Using primers derived from the known rat cDNA sequence for COMT, we have used the polymerase chain reaction to produce an amplified DNA fragment corresponding to the complete coding region of the rat gene. With this fragment as a probe, we have hybridized DNAs from two panels consisting of human/rodent and human/hamster somatic cell hybrids carrying various translocations and deletions to refine the chromosomal location of human COMT. Southern blot analysis indicates that the human COMT gene is localized to 22q11.1----q11.2, a region to which several anonymous DNA sequences, but until now, no structural genes, have been assigned.

Catechol O-Methyltransferase↗
PubMed1994

Characterization of two high molecular weight catechol-containing glycoproteins from pharate pupal cuticle of the tobacco hornworm, Manduca sexta.

Two high molecular weight cuticular proteins (MSCP120 and MSCP246) were extracted in acidic guanidine hydrochloride solution from tanning abdominal cuticle of Manduca sexta pharate pupae and purified by size exclusion high performance liquid chromatography. The apparent molecular weights were ca. 120 and 246 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Both proteins contained high levels of glutamate/glutamine, glycine, serine, alanine and aspartate/asparagine. MSCP120 was enriched in histidine relative to MSCP246, but the reverse was true for valine and proline. Small quantities of beta-alanine and 3,4-dihydroxyphenylalanine (DOPA), as well as other catechols and carbohydrates, also were detected in the hydrolysates. The proteins became radiolabeled when [1-14C]-beta-alanine was injected into pharate pupae, presumably by the formation of adducts with N-beta-alanyldopamine metabolites during sclerotization. Mild acid hydrolysis released N-beta-alanylnorepinephrine and 3,4-dihydroxyphenylketoethanol from both proteins. Strong acid hydrolysis yielded predominantly 3,4-dihydroxyphenylketoethylamine (arterenone), but also DOPA and dopamine. The N-terminal amino acid sequences of the two cuticular proteins were dissimilar, and that of MSCP246 was more hydrophobic than MSCP120. Both of these proteins were glycosylated with glucose, N-acetylglucosamine and traces of N-acetylgalactosamine, and MSCP246 also contained galactose. These structural glycoproteins, which occur in cuticle undergoing sclerotization, apparently react post-translationally with quinonoid tanning agents to yield catecholamine-protein adducts. Small amounts of peptidyl DOPA probably are formed by hydroxylation of tyrosyl residues. Results from this study are consistent with the hypothesis that these catechol-containing glycoproteins participate in cross-linking reactions in M. sexta pupal cuticle during sclerotization.

Amino Acids↗
PubMed1996

Synthesis and in vitro antibacterial activity of spermidine-based mixed catechol- and hydroxamate-containing siderophore--vancomycin conjugates.

The first antibiotic conjugates of vancomycin (1) and siderophore analogues containing spermidine-based catechol ligands (conjugate 11) as well as mixed catechol and hydroxamate ligands (conjugate 13) are described. The design of the conjugates was based on the earlier observation that conjugation of siderophore components to beta-lactam antibiotics induced active iron transport-mediated drug delivery. The novel conjugates (11 and 13) were synthesized by selective acylation of the primary amino group of 1. Preliminary biological studies indicated that siderophore modified vancomycins lost some activity (4- to 16-fold) against Gram-positive bacteria relative to vancomycin itself, and were generally similar to vancomycin in activity against Gram-negative bacteria under iron-sufficient conditions. However, under iron-depleted conditions which mimic human serum, conjugate 11 displayed enhanced antibacterial activity against an antibiotic hypersensitive strain of Pseudomonas aeruginosa.

Anti-Bacterial Agents↗
PubMed2004

Structural roles of the active site iron(III) ions in catechol 1,2-dioxygenases and differential secondary structure changes in isoenzymes A and B from Acinetobacter radioresistens S13.

The reversible active site metal ion removal process for two catechol 1,2-dioxygenase isoenzymes (IsoA and IsoB) isolated from Acinetobacter radioresistens S13 has been monitored using circular dichroism and fluorescence spectroscopic techniques. IsoA and IsoB are homodimers, containing one iron(III) ion per subunit. Their amino acid sequence identity is 48.4%. Previous experiments suggested that structural diversities could be responsible for the differential thermal and pH stabilities of the two isoenzymes and of their distinct demetallation kinetics. The far-UV CD spectra of IsoA and IsoB catechol 1,2-dioxygenases from A. radioresistens S13 provide information on their secondary structures. IsoB appears to have a content of alpha-helices higher than IsoA. Upon metal ion removal, both proteins reversibly lose part of their secondary structure following distinct pathways. CD spectra simulations allowed us to estimate the content of alpha-helices, beta-sheets, and turns for each isoenzyme and to monitor the secondary structure rearrangements. The metal ion withdrawal has large influence on the secondary structure: in particular a significant reduction of alpha-helices content is observed for both isoenzymes. Intrinsic fluorescence emission spectra clearly support such results, adding information on the local environment changes of the tryptophan residues. The positioning of Trp250 in IsoB has been shown to be of particular interest for monitoring the local structure changes occurring upon metal ion removal. For the first time these studies allow to underline the role of active site iron ions on dioxygenases folding and stability, further evidencing the differences in structural assembling between the two isoenzymes from A. radioresistens S13.

Acinetobacter↗
PubMed2003

Nrf2, not the estrogen receptor, mediates catechol estrogen-induced activation of the antioxidant responsive element.

The antioxidant responsive element (ARE) plays an important role in the gene expression of phase II detoxification enzymes, such as NAD(P)H:quinone oxidoreductase 1 (NQO1), and NF-E2-related factor2 (Nrf2) is the transcription factor for the ARE-driven genes. Interestingly, estrogen receptor (ER) was reported to increase NQO1 gene expression through the ARE. In this study, we investigated the role of ER and Nrf2 in ARE activation using IMR-32 cells and mouse primary astrocytes. Among tested estrogen-related compounds, only catechol estrogens (i.e. 4-hydroxyestradiol) activated the ARE. Since 4-hydroxyestradiol-induced ARE activation was not inhibited by either 17beta-estradiol or tamoxifen, and overexpression of ER-alpha decreased 4-hydroxyestradiol-induced ARE activation, ARE activation by catechol estrogen was independent of ER. Nrf2, however, was very important in the 4-hydroxyestradiol-induced ARE activation. 4-Hydroxyestradiol did not activate the ARE in Nrf2 knockout (-/-) primary astrocytes, but did activate the ARE when Nrf2 was transfected into Nrf2-/- astrocytes. In addition, dominant negative Nrf2 completely blocked 4-hydroxyestradiol-induced ARE activation in Nrf2+/+ astrocytes, and only 4-hydroxyestradiol induced Nrf2 nuclear translocation in IMR-32 cells. A selective phosphatidylinositol 3-kinase (PI3-kinase) inhibitor (LY294002) blocked 4-hydroxyestradiol-induced Nrf2 nuclear translocation and NQO1 activity induction in IMR-32 cells. Taken together, these observations suggest that 4-hydroxyestradiol activates the ARE by a PI3-kinase-Nrf2 dependent mechanism, not involving ER.

Animals↗
PubMed2006

Bioelectrocatalytic properties of lignin peroxidase from Phanerochaete chrysosporium in reactions with phenols, catechols and lignin-model compounds.

Bioelectrocatalytic reduction of H(2)O(2) catalysed by lignin peroxidase from Phanerochaete chrysosporium (LiP) was studied with LiP-modified graphite electrodes to elucidate the ability of LiP to electro-enzymatically oxidise phenols, catechols, as well as veratryl alcohol (VA) and some other high-redox-potential lignin model compounds (LMC). Flow-through amperometric experiments performed at +0.1 V vs. Ag|AgCl demonstrated that LiP displayed significant bioelectrocatalytic activity for the reduction of H(2)O(2) both directly (i.e., in direct electron transfer (ET) reaction between LiP and the electrode) and using most of studied compounds acting as redox mediators in the LiP bioelectrocatalytic cycle, with a pH optimum of 3.0. The bioelectrocatalytic reduction of H(2)O(2) mediated by VA and effects of VA on the efficiency of bioelectrocatalytic oxidation of other co-substrates acting as mediators were investigated. The bioelectrocatalytic oxidation of phenol- and catechol derivatives and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonate) by LiP was independent of the presence of VA, whereas the efficiency of the LiP bioelectrocatalysis with the majority of other LMC acting as mediators increased upon addition of VA. Special cases were phenol and 4-methoxymandelic acid (4-MMA). Both phenol and 4-MMA suppressed the bioelectrocatalytic activity of LiP below the direct ET level, which was, however, restored and increased in the presence of VA mediating the ET between LiP and these two compounds. The obtained results suggest different mechanisms for the bioelectrocatalysis of LiP depending on the chemical nature of the mediators and are of a special interest both for fundamental science and for application of LiP in biotechnological processes as solid-phase bio(electro)catalyst for decomposition/detection of recalcitrant aromatic compounds.

Catalysis↗
PubMed2004

A colormetric assay for catechol-O-methyltransferase.

A series of catechol diazo dyes were synthesized and tested as substrates for the enzyme catechol-O-methyltransferase (COMT) with the aim of developing a sensitive HPLC assay method using visible wavelength light detection. A method was developed which allowed for the determination of the two regioisomeric methylated products of the COMT catalyzed reaction of 4-[(3,4-dihydroxyphenyl)azo]benzenesulfonate with S-adenosylmethionine (AdoMet). Separation of the assay components was achieved by reverse phase chromatography using an isocratic mobile phase. No pre-preparation of the assay samples was required.

Azo Compounds↗
PubMed2005

Synthesis and evaluation of bifunctional nitrocatechol inhibitors of pig liver catechol-O-methyltransferase.

Bifunctional compounds were tested in vitro as potential inhibitors of pig liver catechol-O-methyltransferase (COMT) with respect to the catechol substrate 4-[(3,4-dihydroxyphenyl)azo]benzenesulfonate. The bifunctional compounds were a composite of either two nitrocatechols or one nitrocatechol and one phenol, linked by amide bonds to a spacer unit comprising two to five methylene groups. The unsymmetrical compounds N-[2-(4-hydroxybenzoylamine)ethyl]-3,4-dihydroxy-5-nitrobenzamide], N-[3-(4-hydroxybenzoyl-amine)propyl]-3,4-dihydroxy-5-nitrobenzamide] and N-[5-(4-hydroxybenzoylamine)pentyl]-3,4-dihydroxy-5-nitrobenzamide] demonstrated strong inhibitory action against COMT with K(i) values in the 100 nM range. In comparison, the monofunctional nitrocatechol analogues of these compounds had K(i) values that were significantly higher.

Animals↗
PubMed2003

Catechol-substituted L-chicoric acid analogues as HIV integrase inhibitors.

HIV integrase catalyzes the integration of HIV DNA copy into the host cell DNA, which is essential for the production of progeny viruses. L-Chicoric acid and dicaffeoylquinic acids, isolated from plants, are well known potent inhibitors of HIV integrase. The common structural features of these inhibitors are caffeic acid derivatives connected to tartaric acid or quinic acid through ester bonds. In the present study, we have synthesized and tested the inhibitory activities of a new type of HIV IN inhibitors, which has catechol groups in place of caffeoyl groups in the structure of L-chicoric acid. Upon substitution of catechol groups at succinic acid, pyrrole-dicarboxylic acid, maleimide or maleic anhydride, the inhibitory activities (IC(50)=3.8-23.6 microM) were retained or remarkably increased when compared to parent compound L-chicoric acid (IC(50)=13.7 microM).

Caffeic Acids↗
PubMed2005

Functional and structural comparisons of cysteine residues in the Val108 wild type and Met108 variant of human soluble catechol O-methyltransferase.

Catechol O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. This enzyme is genetically polymorphic with a wild type and a variant form. Numerous epidemiological studies have shown that the variant form is associated with an increased risk of developing estrogen-associated cancers and a wide spectrum of mental disorders. There are seven cysteine residues in human S-COMT, all of which exist as free thiols and are susceptible to electrophilic attack and/or oxidative damage leading to enzyme inactivation. Here, the seven cysteine residues were systematically replaced by alanine residues by means of site-directed mutagenesis. The native forms and cysteine/alanine mutants were assayed for enzymatic activity, thermal stability, methylation regioselectivity, and reactivity of cysteine residues to thiol reagent. Our data showed that although there is only one encoding base difference between these two COMT forms, this difference might induce structural changes in the local area surrounding some cysteine residues, which might further contribute to the different roles they might play in enzymatic activity, and to the different susceptibility to enzyme inactivation.

Catechol O-Methyltransferase↗
PubMed2005

Polymorphic catechol-O-methyltransferase gene, duration of estrogen exposure, and breast cancer risk: a nested case-control study in Taiwan.

BACKGROUND: Polymorphic catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol estrogens, which are hypothesized to participate in estrogen-induced carcinogenesis. METHODS: We examined 87 cases and 341 population controls in Taiwan to determine the association between the functional genetic Val158Met polymorphism in membrane-bound form of COMT gene and female breast cancer risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by conditional logistic regression. RESULTS: There was no overall association between COMT genotype and individual susceptibility to breast cancer. However, COMT-L variant genotypes appear to pose increased risk of breast cancer in women with greater duration from menarche to first full-term pregnancy (>8 years) (OR, 2.67; 95% CI, 1.00-7.36). CONCLUSIONS: This study based on limited sample sizes suggests that there may be no overall association of COMT genotype with breast cancer, but the COMT-L allele could pose enhanced risk of breast cancer in the presence of relevant environmental exposures, as most low penetrance gene are expected to act through gene-environment interactions.

Adult↗
PubMed2005

Indirect chemiluminescence detection for capillary zone electrophoresis of monoamines and catechol using luminol-k3[Fe(CN)6] system.

Indirect chemiluminescence (ICL) detection for capillary electrophoresis (CE) of monoamines and catechol using luminol-K3 [Fe(CN)6] system was described. A strong and stable background chemiluminescence (CL) signal can be generated by luminol-K3 [Fe(CN)6] reaction. Based on the principle of that some phenolic compounds may be oxidized in the presence of K3 [Fe(CN)6], quenching effect of catecholamines for luminol-K3[Fe(CN)6] CL reaction results in a quantifiable decrease in the background signal. The conditions for CE separation and the CL detection for four standard catecholamines were systematically investigated using a homemade CE-ICL system. Under the optimum conditions, the detection limits of dopamine (DA), epinephrine (EP), norepinephrine (NE) and catechol (CA) were determined to be 0.18 mciroM 0.39 microM 0.48 microM and 0.09 microM, respectively. It also has been successfully applied to analyze seven pharmaceutical samples and seven human urine samples.

Adult↗