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 1,153 records · Page 64Linked to original sources
PubMed1991

Immunoaffinity purification and partial amino acid sequence analysis of catechol-O-methyltransferase from pig liver.

Monoclonal antibodies (mAbs) against the soluble form (S-COMT) of catechol-O-methyltransferase (COMT, EC 2.1.1.6) were produced using a purified preparation of the enzyme from pig liver as antigen. The selected monoclonal antibodies recognized the enzyme with different capacities. One of them (Co60-1B/7) showed a significant cross reaction with S-COMT from rat and human liver. A protein band of 23 kDa was recognized by the mAbs on Western blots of the soluble fraction of pig liver. The mAbs were also able to recognize the membrane-bound form of the enzyme, which was found to be mainly localized in the microsomal fraction of pig and rat liver as well as of the human hepatoma cell line Hep G2. The protein bands detected in microsomes had a molecular mass of 26 kDa in pig and rat liver and displayed a slightly higher molecular mass (29 kDa) in the Hep G2 cell line. A single step method for the immunoaffinity purification of pig liver S-COMT was developed by using a Sepharose 4B column to which the mAb Co54-5F/8 was covalently coupled. Acid elution conditions were optimized to obtain the enzyme in active form with a good yield. SDS-PAGE analysis of the purified preparation revealed a single protein band with a molecular mass of 23 kDa with 154-fold enrichment in enzyme activity over the starting material. Since the N-terminus was blocked, purified enzyme preparations were cleaved with trypsin. Two fragments of 22 and 33 amino acids in length could be sequenced by Edman degradation.

Amino Acid Sequence↗
PubMed1989

Consequences of monoamine oxidase inhibition: increased vesicular accumulation of dopamine and norepinephrine and increased metabolism by catechol-O-methyltransferase and phenolsulfotransferase.

1. Male Sprague-Dawley rats were injected with saline, L-Dopa or pargyline. 2. Synaptic vesicles were prepared from whole brain homogenates. Catecholamines and their metabolites in brain tissues and in synaptic vesicles were measured by high performance liquid chromatography with electrochemical detection. 3. L-Dopa administration raised brain dopamine markedly but did not significantly change dopamine and norepinephrine in the vesicular fraction. 4. The dopamine increase following L-Dopa was not accompanied by any change in normetanephrine, 3-methoxytyramine or dopamine sulfate. 5. In comparison to the control rats and rats injected with L-Dopa, pargyline-treated rats exhibited significantly higher vesicular norepinephrine and dopamine. 6. The dopamine and norepinephrine increases following pargyline treatment were accompanied by significant increases in 3-methoxytyramine, normetanephrine and dopamine sulfate. 7. The increases in vesicular dopamine and norepinephrine may be the origin of their increased metabolism by extraneuronal enzymes, catechol-O-methyltransferase and phenolsulfotransferase.

Animals↗
PubMed1979

Toxic interaction between narcotic analgesics and inhibitors of catechol-O-methyltransferase.

A lethal synergism between morphine and tropolone, an inhibitor of catechol-O-methyltransferase, was previously noted in adult male Holtzman rats. The present research demonstrates that this phenomenon generalizes across factors of sex, age, strain (Sprague--Dawley, Wistar) and species (Swiss albino mice). Acute toxicity was also significantly increased (1.5--1.9 times) in the case of codeine, methadone, meperidine and levorphanol, but to a lesser extent than for morphine (4.0 times) in the S-D strain. Another COMT inhibitor, 3,5-dihydroxy-4-methoxybenzoic acid, interacted with morphine in S-D rats to an equal degree as did tropolone. Post-treatment with 1 mg/kg of naloxone in rats or naltrexone in mice reduced the high lethality associated with morphine plus tropolone. There was a pronounced lowering of whole brain norepinephrine (NE) level after morphine plus tropolone in Wistar rats with doses of each component that alone caused no change in NE. Brain dopamine (DA) was elevated by tropolone and by its combination with morphine. Each drug alone caused slight lowering of brain serotonin. Enhancement by tropolone of the toxicity of (+)-amphetamine in mice and rats was of similar magnitude as for morphine. The possible role of brain NE and/or DA in the sensitivity to acute toxic effects of opioids in rodents is suggested by these data, as well as a parallel in this regard with amphetamine-type stimulants.

Aging↗
PubMed1990

Catechol estrogen formation in the mouse uterus and its role in implantation.

Estradiol-2/4-hydroxylase (E-2/4-H) activity was determined in the mouse uterus during early pregnancy as well as in ovarian steroid hormone-treated ovariectomized uterus. Under the assay conditions used, E-4-H was the predominant catechol estrogen-forming monooxygenase enzyme. The inhibition of E-4-H activity by SKF-525A, metyrapone and alpha-naphthoflavone suggested involvement of cytochrome P450-dependent monooxygenases. A haloestrogen, 2-fluoroestradiol (2-FL-E2), also inhibited this activity. During the peri-implantation period, no change in uterine E-4-H activity was noted on the morning of days 2 through 5, but the activity significantly (P less than 0.01) increased in the afternoon of day 4 of pregnancy. A single injection of estradiol-17 beta (E2, 100 ng/mouse) to ovariectomized mice significantly (P less than 0.01) elevated the level of E-4-H activity at 24 h as did injections of progesterone (P4, 2 mg/mouse) for 2 days. When 2 days of P4 (2 mg/mouse) treatment was combined with a single injection of E2 (20 ng/mouse), E-4-H activity increased 1.3-fold (P less than 0.05) by 24 h above that of P4 treatment alone. Dexamethasone (200 micrograms/mouse) and cholesterol (2 mg/mouse) treatment for 2 days had no effect on E-4-H activity. Thus, the stimulatory effect of P4 and E2 on E-4-H activity appeared to be specific. The increased activity of uterine E-4-H prior to implantation on day 4 evening and the modulation of its activity by P4 and/or E2 suggest an involvement of 4-hydroxyestradiol in embryo implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Catechol-O-methyltransferase (COMT) in rat brain: immunoelectron microscopic study with an antiserum against rat recombinant COMT protein.

Localization of catechol-O-methyltransferase (COMT) in rat cerebral cortex, neostriatum and cerebellar cortex was studied with preembedding immunoelectron microscopy using a specific antiserum raised against rat recombinant COMT protein. In all areas, immunoreactivity was found both in astrocytes and in neuronal processes. Reaction product was seen in the cytoplasm and in association with tubular structures of dendritic processes. Immunoreactivity was also located postsynaptically in dendritic spines and associated with the postsynaptic membrane. Strong immunoreaction was also seen in the cytoplasm of ependymal cells lining the ventricles, and in tanycytes in median eminence. The results suggest that postsynaptic dendritic spines and astrocytic processes may be the sites of catecholamine inactivation by COMT in rat brain.

Animals↗
PubMed1983

Platelet monoamine oxidase and erythrocyte catechol-o-methyltransferase activity in alcoholism and controlled abstinence.

This study substantiates previous reports that low platelet monoamine oxidase (MAO) activity is associated with alcoholism. Catechol-o-methyltransferase (COMT) activity in erythrocytes of alcoholics did not differ from that of controls. In 20 male alcoholics low platelet MAO activity was found during the first 3 days after hospitalization. The MAO activity increased in the next 2 weeks of abstinence and then tended to decrease again.

Adult↗
PubMed1990

Molecular cloning and characterization of rat liver catechol-O-methyltransferase.

The coding sequence of rat liver catechol-O-methyl-transferase (COMT; EC 2.1.1.6) was determined from rat cDNA and genomic libraries were screened with DNA probes and specific antiserum. The open reading frame consisted of 663 nucleotides coding for a 221-amino acid (aa) polypeptide with a deduced Mr of 24,747. No obvious hydrophobic signal sequence, membrane-spanning domains, or potential N-glycosylation sites were found in this sequence. The identity of the clone and the accuracy of the sequence was verified by direct aa sequencing of the tryptic peptides derived from the purified rat liver enzyme. Primer extension analysis showed that the transcription start point of the rat liver COMT mRNA was 450 bp upstream from the translation start codon. A putative polyadenylation signal (ATTAAA) was found in the 3'-noncoding region. The predicted size of the COMT transcript was 1.8-2.0 kb, which could be confirmed from Northern hybridization analyses of the isolated rat liver mRNA. One polypeptide of 25 kDa, could be immunoprecipitated with anti-COMT antibody from in vitro translation of rat liver mRNA. Employing the DNA blot analysis only one COMT-encoding gene was found in the rat genome.

Amino Acid Sequence↗
PubMed1991

Sequence of the plasmid-encoded catechol 1,2-dioxygenase-expressing gene, pheB, of phenol-degrading Pseudomonas sp. strain EST1001.

Phenol monooxygenase (PMO) and catechol 1,2-dioxygenase (C12O), the two first enzymes of the phenol-degradation pathways, are encoded by a 3.4-kb DNA fragment cloned from Pseudomonas sp. EST1001 plasmid DNA. We have previously shown that activation of the cloned genes in Pseudomonas putida PaW85 is controlled by insertion of the 17-kb transposon, Tn4652, from the host chromosome into the plasmid carrying these genes [Kivisaar et al. Plasmid 24 (1990) 25-36]. Transcription of the DNA encoding PMO (pheA) and C12O (pheB) is activated by a promoter located on a 0.2-kb SacI-ClaI fragment from Tn4652. We have determined the nucleotide sequence of pheB. The 906-bp gene encodes a protein product with a deduced Mr of 33,362. The relationship between the pheB gene and other C12O-encoding genes has been shown: comparison of the pheB sequence with sequences of catA of Alcaligenes calcoaceticus, tfdC of A. eutrophus and clcA of P. putida demonstrated that there are conserved residues in all the four protein products of these genes.

Amino Acid Sequence↗
PubMed1996

Plasmids with erythromycin resistance and catechol 2,3-dioxygenase- or beta-galactosidase-encoding gene cassettes for use in Neisseria spp.

Four new plasmids containing the ermC' (encoding a methyltransferase which confers resistance to erythromycin), xylE-ermC' (xylE, encoding catechol 2,3-dioxygenase) and lacZ-ermC' cassettes have been constructed. The 10-bp gonococcal uptake sequence has been placed downstream from ermC' to facilitate the delivery of these cassettes into pathogenic Neisseria spp. Several restriction sites have been placed to flank the cassettes to allow their excision and directional cloning. These plasmids will provide valuable tools for constructing insertional mutants and transcriptional fusions in Neisseria spp. or other bacteria.

Anti-Bacterial Agents↗
PubMed1991

High-performance liquid chromatographic determination, with ultraviolet detection, of S-adenosyl-L-methionine and S-adenosyl-L-homocysteine in rat tissues and simultaneously of normetanephrine and metanephrine for phenylethanolamine-N-methyltransferase or catechol-O-methyltransferase activities.

A high-performance liquid chromatographic method, with ultraviolet detection, for the determination of S-adenosyl-L-methionine and S-adenosyl-L-homocysteine, and simultaneously of normetanephrine and metanephrine, is presented. The separation was carried out by reversed-phase ion-pair isocratic chromatography. This procedure was applied to the study of the content of S-adenosyl-L-methionine and S-adenosyl-L-homocysteine in rat brain and adrenal glands and to the measurement of phenylethanolamine-N-methyltransferase or catechol-O-methyltransferase activities in rat adrenal gland.

Adrenal Glands↗
PubMed1992

Application of an organic solvent extraction to the determination of catechol-O-methyltransferase activity by high-performance liquid chromatography in human mononuclear cells.

We report here a method for measuring mononuclear cell catechol-O-methyltransferase (COMT) activity which is ideally adapted to clinical studies. The method measures the O-methylation of dopamine to 3-methoxytyramine and 4-methoxy-3-hydroxyphenethylamine. Whole mononuclear cell sonicate is incubated with saturating concentrations of dopamine, S-adenosyl-L-methionine and magnesium chloride in sodium-potassium phosphate buffer at pH 7.3. An organic solvent extraction using ethyl acetate is then used for product separation, followed by high-performance liquid chromatography with electrochemical detection for product separation and quantification. This method allows both O-methylated products, 3-methoxytyramine and 4-methoxy-3-hydroxyphenethylamine, to be isolated and quantified separately. The apparent Michaelis constants for dopamine and S-adenosyl-L-methionine using this method are similar to values reported previously (0.51 and 14 microM, respectively). The optimal concentration of magnesium chloride is eight to ten times higher than previously reported. No endogenous inhibitors were apparent using this assay. The within-day coefficient of variation using this method is 7% when measuring 3-methoxytyramine and 5% when measuring 4-methoxy-3-hydroxyphenethylamine. The between-day coefficient of variation is 11%. Mononuclear cell COMT activity can be detected using protein concentrations as low as 0.75 mg/ml, corresponding to 2-3 ml of whole blood. The small amount of blood required per sample allows multiple sample analysis from a single patient, including infants.

Adult↗
PubMed1995

Improved assay of reaction products to quantitate catechol-O-methyltransferase activity by high-performance liquid chromatography with electrochemical detection.

We applied coulometric detection (three electrochemical electrodes in series) to quantitate vanillic acid and isovanillic acid using reversed-phase HPLC. The formation of these reaction products from dihydroxybenzoic acid was used as a precise and reproducible measure of catechol-O-methyltransferase (COMT) activity in striatal homogenates and recombinant membrane-bound COMT protein. This detection system has a higher sensitivity (0.5 pmol per injection) than a single-cell amperometric detection. As in a previous method, the deproteinized supernatants of the COMT assay could be injected directly onto the HPLC system allowing the handling of a large number of samples in one day.

Animals↗
PubMed1996

Purification methods of mammalian catechol-O-methyltransferases.

The protein purification strategies used for obtaining homogeneous rat and human soluble catechol-O-methyltransferase (S-COMT) polypeptides are reviewed. Expression and purification of recombinant rat and human S-COMT in Escherichia coli and for human S-COMT in baculevirus-infected insect cells made it possible to elucidate the S-COMT polypeptides in more detail. The application of these purification methods has allowed the crystallization of the rat S-COMT protein and the analysis of the kinetic properties of the enzyme in great detail. The availability of the pure S-COMT protein together with the structural data has also greatly enhanced the development of more potent COMT inhibitors.

Amino Acid Sequence↗
PubMed1995

Neuronal and non-neuronal catechol-O-methyltransferase in primary cultures of rat brain cells.

Previous biochemical and histochemical studies have suggested that catechol-O-methyltransferase (COMT) is a predominantly glial enzyme in the brain. The aim of this work was to study its localization and molecular forms in primary cultures, where cell types can be easily distinguished with specific markers, COMT immunoreactivity was studied in primary astrocytic cultures from newborn rat cerebral cortex, and in neuronal cultures from rat brain from 18-day-old rat embryos using antisera against rat recombinant COMT made in guinea pig. Double-staining studies with specific cell markers to distinguish astrocytes, neurons and oligodendrocytes were performed. COMT immunoreactivity colocalized with a specific oligodendrocyte marker galactocerebroside in cells displaying oligodendrocyte morphology, flat cells displaying type-1 astrocyte morphology and glial fibrillary acidic protein, in branched cells displaying type-2 astrocyte morphology and in cell bodies of neurons, the processes of which displayed neurofilament immunoreactivity. Western blots detected both soluble 24 kDa and membrane-bound 28-kDa COMT proteins in neuronal and astrocyte cultures. The results suggest that COMT is synthesized by cultured astrocytes, oligodendrocytes and neurons.

Animals↗
PubMed1991

The development of a catechol enzyme electrode and its possible use for the diagnosis and monitoring of neural crest tumours.

A catechol enzyme electrode is described, in which a Clark-type oxygen electrode is coupled to immobilised polyphenol oxidase in albumin cross linked with glutaraldehyde on a dialysis membrane. Electrode calibration, response time, pH response profile, stability, detection limit and selectivity are evaluated and the feasibility of using the electrode for the measurement of catecholamines in the urine of patients with neural crest tumours is assessed.

Biosensing Techniques↗
PubMed2007

High systolic blood pressure is associated with Val/Val genotype in the catechol-o-methyltransferase gene. The Nord-Trøndelag Health Study (HUNT).

BACKGROUND: The catechol-O-methyltransferase (COMT) gene contains a functional polymorphism, Val158Met. A few studies on animals have shown a relationship between the COMT gene and BP, but whether this exists in human beings is unclear. The aim of this study was to evaluate the relationship between codon 158 COMT gene polymorphism and BP in a population-based cohort. METHODS: In the 1995-97 Nord-Trøndelag Health Study (HUNT), the association between Val/Met polymorphism at the COMT gene and BP was evaluated in a group of 2966 nondiabetic individuals. RESULTS: Among the 2591 individuals without current use of antihypertensive drugs, systolic BP > or =140 mm Hg was more likely among persons with Val/Val genotype compared with the other genotypes (44.8% v 39.1%, P = .02). In the multivariate analysis the prevalence odds ratio for having the Val/Val genotype was 1.63 (95% CI = 1.18 to 2.24) among individuals with systolic BP > or =160 mm Hg compared with those with systolic BP <140 mm Hg. Val/Val genotype was also more likely (OR = 1.30, 95% CI = 1.04 to 1.63) among individuals with hypertension (as defined by use of antihypertensive medication, systolic BP > or =140 mm Hg, or diastolic BP > or =90 mm Hg) than among those with normal BP. CONCLUSIONS: Based on the study findings, the Val/Val genotype appears to be associated with a higher prevalence of increased systolic BP compared with the Met/Met or Met/Val genotypes at the COMTgene.

Adult↗
PubMed2006

Catechol estrogen quinones as initiators of breast and other human cancers: implications for biomarkers of susceptibility and cancer prevention.

Exposure to estrogens is associated with increased risk of breast and other types of human cancer. Estrogens are converted to metabolites, particularly the catechol estrogen-3,4-quinones (CE-3,4-Q), that can react with DNA to form depurinating adducts. These adducts are released from DNA to generate apurinic sites. Error-prone base excision repair of this damage may lead to the mutations that can initiate breast, prostate and other types of cancer. The reaction of CE-3,4-Q with DNA forms the depurinating adducts 4-hydroxyestrone(estradiol) [4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua. These two adducts constitute more than 99% of the total DNA adducts formed. Increased levels of these quinones and their reaction with DNA occur when estrogen metabolism is unbalanced. Such an imbalance is the result of overexpression of estrogen activating enzymes and/or deficient expression of the deactivating (protective) enzymes. This unbalanced metabolism has been observed in breast biopsy tissue from women with breast cancer, compared to control women. Recently, the depurinating adduct 4-OHE1(E2)-1-N3Ade has been detected in the urine of prostate cancer patients, but not in urine from healthy men. Mutagenesis by CE-3,4-Q has been approached from two different perspectives: one is mutagenic activity in the lacI reporter gene in Fisher 344 rats and the other is study of the reporter Harvey-ras gene in mouse skin and rat mammary gland. A-->G and G-->A mutations have been observed in the mammary tissue of rats implanted with the CE-3,4-Q precursor, 4-OHE2. Mutations have also been observed in the Harvey-ras gene in mouse skin and rat mammary gland within 6-12 h after treatment with E2-3,4-Q, suggesting that these mutations arise by error-prone base excision repair of the apurinic sites generated by the depurinating adducts. Treatment of MCF-10F cells, which are estrogen receptor-alpha-negative immortalized human breast epithelial cells, with E2, 4-OHE2 or 2-OHE2 induces their neoplastic transformation in vitro, even in the presence of the antiestrogen ICI-182,780. This suggests that transformation is independent of the estrogen receptor. The transformed cells exhibit specific mutations in several genes. Poorly differentiated adenocarcinomas develop when aggressively transformed MCF-10F cells are selected and injected into severe combined immune depressed (SCID) mice. These results represent the first in vitro/in vivo model of estrogen-induced carcinogenesis in human breast epithelial cells. In other studies, the development of mammary tumors in estrogen receptor-alpha knockout mice expressing the Wnt-1 oncogene (ERKO/Wnt-1) provides direct evidence that estrogens may cause breast cancer through a genotoxic, non-estrogen receptor-alpha-mediated mechanism. In summary, this evidence strongly indicates that estrogens can become endogenous tumor initiators when CE-3,4-Q react with DNA to form specific depurinating adducts. Initiated cells may be promoted by a number of processes, including hormone receptor stimulated proliferation. These results lay the groundwork for assessing risk and preventing disease.

Animals↗
PubMed2004

Catechol-O-methyltransferase polymorphism alters hypothalamic-pituitary-adrenal axis responses to naloxone: a preliminary report.

BACKGROUND: A common polymorphism in the catechol-O-methyltransferase gene involves a valine to methionine mutation that results in a threefold to fourfold decrease in enzyme activity. This polymorphism has been associated with altered mu-opioid receptor binding potential and prefrontal cognitive performance, as well as risk for several neuropsychiatric conditions. We hypothesized that subjects homozygous for the low-activity allele would have greater hypothalamic-pituitary-adrenal axis responses to opioid blockade than subjects with the high-activity allele. METHODS: Forty-six healthy adults were genotyped and underwent a procedure in which adrenocorticotropin hormone and cortisol responses to the opioid antagonist naloxone were examined. RESULTS: Findings showed that adrenocorticotropin hormone and cortisol responses were greater in subjects with the methionine/methionine genotype compared to subjects homozygous or heterozygous for the valine allele. CONCLUSIONS: These findings suggest that individual differences in catecholamine metabolism may impact hypothalamic-pituitary-adrenal axis function and may play a pharmacogenetic role in responses to naloxone.

Adolescent↗