Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plant cell walls are composed of a large number of complex polysaccharides, which contain at least 13 different monosaccharides in a multitude of linkages. This structural complexity of cell wall components is paralleled by a large number of predicted glycosyltransferases in plant genomes, which can be grouped into several distinct families based on conserved sequence motifs (B. Henrissat, G.J. Davies [2000] Plant Physiol 124: 1515-1519). Despite the wealth of genomic information in Arabidopsis and several crop plants, the biochemical functions of these coding regions have only been established in a few cases. To lay the foundation for the genetic and biochemical characterization of putative glycosyltransferase genes, we conducted a phylogenetic and expression analysis on 10 predicted coding regions (AtGT11-20) that are closely related to the MUR3 xyloglucan galactosyltransferase of Arabidopsis. All of these proteins contain the conserved sequence motif pfam 03016 that is the hallmark of the beta-d-glucuronosyltransferase domain of exostosins, a class of animal enzymes involved in the biosynthesis of the extracellular polysaccharide heparan sulfate. Reverse transcriptase-polymerase chain reaction and promoter:beta-glucuronidase studies indicate that all AtGT genes are transcribed. Although six of the 10 AtGT genes were expressed in all major plant organs, the remaining four genes showed more restricted expression patterns that were either confined to specific organs or to highly specialized cell types such as hydathodes or pollen grains. T-DNA insertion mutants in AtGT13 and AtGT18 displayed reductions in the Gal content of total cell wall material, suggesting that the disrupted genes encode galactosyltransferases in plant cell wall synthesis.
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PMID:Molecular analysis of 10 coding regions from Arabidopsis that are homologous to the MUR3 xyloglucan galactosyltransferase. 1502 Jul 58

The 5' fragment (1 647 bp) of the cotton glucuronosyltransferase gene (GhGlcAT1) was transcriptionally fused to the beta-glucuronidase (GUS) gene, and functionally analyzed for important regulatory regions controlling gene expression in transgenic tobacco plants. GUS activity analysis revealed that the full-length promoter drives efficient expression of the GUS gene in the root cap, seed coat, pollen grains and trichomes. Exposure of the transgenic tobacco to various abiotic stresses showed that the promoter was mainly responsive to the sugars (glucose and sucrose) as well as gibberellic acid. Progressive upstream deletion analyses of the promoter showed that the region from -281 to +30 bp is sufficient to drive strong GUS expression in the trichomes of shoot, suggesting that the 311 bp region contains all cis-elements needed for trichome-specific expression. Furthermore, deletion analysis also revealed that the essential cis-element(s) for sucrose induction might be located between -635 and -281 bp. In addition, sequence analysis of the regulatory region indicated several conserved motifs among which some were shared with previously reported seed-specific elements and sugar-responsive elements, while others were related with trichome expression. These findings indicate that a 1 647-bp fragment of the cotton GhGlcAT1 promoter contains specific transcription regulatory elements, and provide clues about the roles of GhGlcAT1 in cotton fiber development. Further analyses of these elements will help to elucidate the molecular mechanisms regulating the expression of the GhGlcAT1 gene during fiber elongation.
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PMID:Functional analysis of a cotton glucuronosyltransferase promoter in transgenic tobaccos. 1717 80

Mitiglinide (MGN) is a new potassium channel antagonist for the treatment of type 2 diabetes mellitus. In the present study, a potential metabolic pathway of MGN, via carboxyl-linked glucuronic acid conjugation, was found. MGN carboxyl-glucuronide was isolated from a reaction mixture consisting of MGN and human liver microsomes fortified with UDP-glucuronic acid (UDPGA) and identified by a hydrolysis reaction with beta-glucuronidase and HPLC-MS/MS. Kinetic analysis indicated that MGN from four species had the highest affinity for the rabbit liver microsomal enzyme (K(m)=0.202 mM) and the lowest affinity for the dog liver microsomal enzyme (K(m)=1.164 mM). The metabolic activity (V(max)/K(m)) of MGN to the carboxyl-glucuronidation was in the following order: rabbit>dog>rat>human. With the assessment of MGN glucuronide formation across a panel of recombinant UDP-glucuronosyltransferase (UGT) isoforms (UGT1A3, UGT1A4, UGT1A6, UGT1A9, and UGT2B7), only UGT1A3 and UGT2B7 exhibited high MGN glucuronosyltransferase activity. The K(m) values of MGN glucuronidation in recombinant UGT1A3 and UGT2B7 microsomes were close to those in human liver microsomes. The formation of MGN glucuronidation by human liver microsomes was effectively inhibited by quercetin (substrate for UGT1A3) and diclofenac (substrate for UGT2B7), respectively. The MGN glucuronidation activities in 15 human liver microsomes were significantly correlated with quercetin (r(2)=0.806) and diclofenac glucuronidation activities (r(2)=0.704), respectively. These results demonstrate that UGT1A3 and UGT2B7 are catalytic enzymes in MGN carboxyl-glucuronidation in human liver.
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PMID:Carboxyl-glucuronidation of mitiglinide by human UDP-glucuronosyltransferases. 1735 41

Dextromethorphan (DEM) is a widely used probe drug for human cytochrome P450 2D6 isozyme activity assessment by measuring the ratio between DEM and its N-demethylated metabolite dextrorphan (DOR). DOR is excreted in urine mainly conjugated to glucuronic acid. Prior to quantification, DOR must be deconjugated to avoid variability caused by the polymorphic glucuronosyltransferase enzyme. A chemical hydrolysis method was optimized using a chemometric approach. Three factors (acid concentration, hydrolysis time and temperature) were selected and simultaneously varied to study their effect on conjugated DOR hydrolysis. Hydrolysis conditions that maximize DOR release without significant degradation of both DEM and DOR were chosen and results were compared to those obtained by enzymatic method using beta-glucuronidase. An HPLC method with fluorescence detection was developed for the simultaneous quantitation of DEM, DOR and levallorphan, used as an internal standard. Separation was performed on a phenyl analytical column (150 mmx4.6 mm i.d., 5 microm) with a mobile phase consisting of 18% acetonitrile and 50 mM phosphoric acid (pH 3). The overall analytical procedure was validated and showed good performances in terms of selectivity, linearity, sensitivity, precision and accuracy. Finally, this assay was used to determine DEM/DOR molar ratios in fibromyalgia patients for the purpose of determining phenotype status for the CYP2D6.
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PMID:Development and validation of a chemical hydrolysis method for dextromethorphan and dextrophan determination in urine samples: application to the assessment of CYP2D6 activity in fibromyalgia patients. 1806 99

The active compounds in the roots of Scutellaria baicalensis Georgi, a traditional Chinese medicinal plant, are mainly flavonoids which have anti-inflammatory, antitumour, and anti-HIV activity, respectively. The increasing annual average temperature has rendered the S. baicalensis plants grown in some ancient producing regions no longer suitable for their medicinal usage. Hydrogen peroxide plays an important role in root responses to abnormal temperature in S. baicalensis. Baicalin and baicalein and antioxidative enzymes were anticipated to detoxify H2O2 in S. baicalensis. Here, we show that abnormal temperatures (10 and 40 degrees C) decreased the content of flavonoids as compared with the normal temperature (30 degrees C), and the transcripts of UDP-glucuronate:baicalein 7-O-glucuronosyltransferase and beta-glucuronidase involved in the interconversion between baicalin and baicalein were affected by the 40-degrees C treatment. High temperature also increased the activities of catalase and peroxidase. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the transcript levels of peroxidase 2, peroxidase 3, monodehydroascorbate reductase 2, and dehydroascorbate reductase were significantly increased under high-temperature conditions. The respective genes would be candidates for improvement of the adaptation of S. baicalensis plants to abnormal temperatures and for regulation of the contents of the active compounds.
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PMID:Flavonoids and antioxidative enzymes in temperature-challenged roots of Scutellaria baicalensis Georgi. 2248 44


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