Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Genetic mapping of the genes (puu) that encode the enzymes catalysing degradation of purines in Pseudomonas aeruginosa strain PAO has been carried out. Mutants that are deficient in adenine deaminase (puuA), guanine deaminase (puuB), xanthine dehydrogenase (puuC), uricase (puuD), allantoinase (puuE), and/or allantoicase (puuF) were isolated and used for the genetic study. Conjugation by FP5 factor and generalized transduction by phage G101 gave the following map locations of these six genes on the chromosome: hisI--puuB--hisII; trpA,B--puuA--ilv202; met9011--catA1--tyu--nar9011--(puuC, puuD, puuE)--puuF. A close linkage among the puuC, puuD and puuE was demonstrated by the transduction.
Mol Gen Genet 1978 Nov 29
PMID:Chromosomal location of genes participating in the degradation of purines in Pseudomonas aeruginosa. 10 42

Neurospora crassa can utilize various purine bases such as xanthine or uric acid and their catabolic products as a nitrogen source. Four classes of mutants which affect the purine degradative pathway were isolated and studied. Mutants of the aln-1 class specifically lack allantoinase, while alc-1 mutants lack allantoicase. Mutants designated as xdh-1 cannot utilize hypoxanthine as a nitrogen source and are presumed to be deficient in xanthine dehydrogenase activity. A regulatory mutant, amr, was found to have only very low, uninduced levels of uricase, allantoinase, and allantoicase. None of these genes are closely linked to each other. The three initial enzymes involved in the catabolism of uric acid are controlled in a complex manner by both induction and repression. Several lines of evidence indicate that the true inducer of uricase and allantoicase is uric acid. The use of the newly isolated mutant strains made it possible to demonstrate that neither allantoin nor allantoic acid could act as inducers. Furthermore, hypoxanthine itself was shown to be ineffective as an inducer although it can be metabolized to form an inducer. A non-metabolizable analogue of uric acid, 8-azaxanthine, is a gratuitous inducer of these enzymes. Uricase and allantoicase were found to be synthesized coordinately, but they were not coordinately regulated with allantoinase. Both uricase and allantoicase are stable enzymes and do not undergo turnover; nor are they subject to feedback inhibition by ammonia. Allantoinase, however, is quite labile both in vivo and in vitro. This enzyme was found to turnover in vivo in the presence of cycloheximide with a half-life of approximately 20 minutes. The amr (for ammonia regulation) mutant cannot utilize a wide range of compounds, including purines, nitrate, and many amino acids as a nitrogen source and also displays a multiple enzyme loss. The amr gene appears to play a major role in the control of nitrogen metabolism. It is postulated that the amr locus encodes a regulatory protein which is required to activate transcription of the structural genes for a group of related enzymes involved in nitrogen metabolism.
Mol Gen Genet 1975 Aug 05
PMID:Genetic and metabolic control of the purine catabolic enzymes of Neurospora crasse. 12 63

Maroon-like homozygotes are completely deficient for xanthine dehydrogenase (XDH) and aldehyde oxidase (AO), however, ma-l is not a structural locus for either enzyme. Quantitative immunoelectrophoresis of ma-l and wild type extracts suggests that the ma-l function must be post-translational. To determine whether the ma-l function involves some direct physical changes in XDH and/or AO the enzymes were characterized with respect to temperature sensitivity and behavior in gel sieving electrophoresis. Since the XDH and AO from complementary ma-l heterozygotes is more thermolabile and different in shape from wild type XDH and AO, we conclude that ma-l is involved in a post-translational modification of these enzymes.
Mol Gen Genet 1979 Apr 17
PMID:Gene expression in Drosophila: post-translational modification of aldehyde oxidase and xanthine dehydrogenase. 28 73

The cnx- group of mutants of Aspergillus nidulans lacks xanthine dehydrogenase (xanthine: NAD+ oxidoreductase, EC 1.2.1.37) and nitrate reductase (EC 1.6.6.3) activities and are thought to be defective in the synthesis of a molybdenum-containing cofactor, 'cnx', common to xanthine dehydrogenase and nitrate reductase [Pateman, J.A., Rever, B.M., Cove, D.J. and Roberts, D.B. (1964) Nature (Lond.) 201, 58-60]. The cnx cofactor has a role in maintaining the aggregated multimeric structure of nitrate reductase [MacDonald, D.W., Cove, D.J. and Coddington, A. (1974) Mol. Gen. Genet. 128, 187-199]. We report here that, in cnx- mutants grown under conditions inducing xanthine dehydrogenase I, a species cross-reacting with antisera to the native enzyme and of half its molecular weight is present, together with cross-reacting molecules of similar molecular weight to the native enzyme. This suggests that the cnx cofactor has a role in maintaining the aggregated structure of xanthine dehydrogenase I. Both cross-reacting species are capable of passing reducing equivalents from NADH to a tetrazolium salt, showing that the cnx cofactor is not necessary for enzymic activity towards NADH.
 ...
PMID:The genetic control of molybdoflavoproteins in Aspergillus nidulans. A xanthine dehydrogenase I half-molecule in cnx- mutant strains of Aspergillus nidulans. 33 Jan 63

In Aspergillus nidulans uric acid can be produced from xanthine via purine hydroxylase I (xanthine dehydrogenase) or via the xanthine alternative pathway (Darlington and Scazzocchio, Biochem. Biophys. Acta, 166, 569--571; 1968). A mutation defective in the xanthine alternative pathway of Aspergillus nidulans is described. By combining this mutation with hxB-20 which results in complete loss of purine hydroxylase I and II activities, but which conserves cross-reacting material, it is possible to block completely uric acid production and thus investigate which are the effective in vivo inducers of three enzymes under the control of the positive regulatory gene uaY: adenine deaminase, purine hydroxylase I (measured as cross-reacting material) and urate oxidase. It is concluded that uric acid is the only effective physiological inducer, while its 2 and 8 thio-analogues serve as gratuitous inducers.
Mol Gen Genet 1978 Sep 08
PMID:A mutation defective in the xanthine alternative pathway of Aspergillus nidulans: its use to investigate the specificity of uaY mediated induction. 36 58

The localization of xanthine oxidoreductase activity was investigated in unfixed cryostat sections of various rat tissues by an enzyme histochemical method which specifically demonstrates both the dehydrogenase and oxidase forms of xanthine oxidoreductase. High activity was found in epithelial cells from skin, vagina, uterus, penis, liver, oral and nasal cavities, tongue, esophagus, fore-stomach and small intestine. In addition activity was demonstrated in sinusoidal cells of liver and adrenal cortex, endothelial cells in various organs and connective tissue fibroblasts. Xanthine oxidoreductase produces urate which is a scavenger of oxygen-derived radicals. Because the enzyme is found in epithelial and endothelial cells which are subject to relatively high oxidant stress, it is postulated that in these cells xanthine oxidoreductase is involved in the antioxidant enzyme defense system. In addition, a possible role for the enzyme in proliferation and differentiation processes is discussed.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:High levels of xanthine oxidoreductase in rat endothelial, epithelial and connective tissue cells. A relation between localization and function? 135 14

Localization of the activity of both the dehydrogenase and oxidase forms of xanthine oxidoreductase were studied in biopsy and postmortem specimens of various human tissues with a recently developed histochemical method using unfixed cryostat sections, poly-(vinyl alcohol) as tissue stabilizator, 1-methoxyphenazine methosulphate as intermediate electron acceptor and Tetranitro BT as final electron acceptor. High enzyme activity was found only in the liver and jejunum, whereas all the other organs studied showed no activity. In the liver, enzyme activity was found in sinusoidal cells and both in periportal and pericentral hepatocytes. In the jejunum, enterocytes and goblet cells, as well as the lamina propria beneath the basement membrane showed activity. The oxidase activity and total dehydrogenase and oxidase activity of xanthine oxidoreductase, as determined biochemically, were found in the liver and jejunum, but not in the kidney and spleen. This confirmed the histochemical results for these organs. Autolytic rat livers several hours after death were studied to exclude artefacts due to postmortem changes in the human material. These showed loss of activity both histochemically and biochemically. However, the percentage activity of xanthine oxidase did not change significantly in these livers compared with controls. The findings are discussed with respect to the possible function of the enzyme. Furthermore, the low conversion rate of xanthine dehydrogenase into xanthine oxidase during autolysis is discussed in relation to ischemia-reperfusion injury.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Distribution of xanthine oxidoreductase activity in human tissues--a histochemical and biochemical study. 136 18

The characterization of mutants that are resistant to the herbicide chlorate has greatly increased our understanding of the structure and function of the genes required for the assimilation of nitrate. Hundreds of chlorate-resistant mutants have been identified in plants, and almost all have been found to be defective in nitrate reduction due to mutations in either nitrate reductase (NR) structural genes or genes required for the synthesis of the NR cofactor molybdenum-pterin (MoCo). The cholorate-resistant mutant of Arabidopsis thaliana, chl2, is also impaired in nitrate reduction, but the defect responsible for this phenotype has yet to be explained. chl2 plants have low levels of NR activity, yet the map position of the chl2 mutation is clearly distinct from that of the two NR structural genes that have been identified in Arabidopsis. In addition, chl2 plants are not thought to be defective in MoCo, as they have near wild-type levels of xanthine dehydrogenase activity, which has been used as a measure of MoCo in other organisms. These results suggest that chl2 may be a NR regulatory mutant. We have examined chl2 plants and have found that they have as much NR (NIA2) mRNA as wild type a variable but often reduced level of NR protein, and one-eighth the NR activity of wild-type plants. It is difficult to explain these results by a simple regulatory model; therefore, we reexamined the MoCo levels in chl2 plants using a sensitive, specific assay for MoCo: complementation of Neurospora MoCo mutant extracts.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Gen Genet 1992 May
PMID:Identification of two tungstate-sensitive molybdenum cofactor mutants, chl2 and chl7, of Arabidopsis thaliana. 153 67

Activated neutrophils cause conversion of xanthine dehydrogenase to its oxidase form (xanthine oxidase) in endothelial cells, the mechanism of which may be related to the cytotoxic effect of activated neutrophils. The elastase inhibitors, elastatinal, alpha 1-antitrypsin, and MeO-Suc-(Ala)2-Pro-Val-CH2Cl, significantly inhibited xanthine dehydrogenase to oxidase conversion by phorbol myristate acetate-stimulated neutrophils without inhibition of neutrophil adherence to the endothelial cell monolayer. The role of elastase in this enzyme conversion process was confirmed by the ability of purified elastase to cause conversion of xanthine dehydrogenase to xanthine oxidase in intact endothelial cells (or cell extracts) without causing cytotoxicity. In contrast, cathepsin G failed to cause conversion. The kinetics of conversion induced by elastase was relatively rapid, being essentially completed by 30 min. Upon removal of elastase, the effect was slowly (greater than 12 h) reversible and could be inhibited by cycloheximide treatment. Exposure of endothelial cells to hypoxia failed to enhance the elastase-induced conversion. Treatment of endothelial cells with Ca2+ ionophores failed to cause conversion of xanthine dehydrogenase to oxidase, suggesting that intracellular Ca(2+)-activated proteases are not sufficient to induce this process. Neutrophil-induced xanthine dehydrogenase to oxidase conversion was inhibited by concomitant treatment with antibodies to CD11b. The results suggest that activated neutrophils induce conversion of xanthine dehydrogenase to oxidase by secretion of elastase in close proximity to the endothelial cells and that this intimate contact between the two cell types enables high local concentrations of elastase to be attained, which are sufficient to cause xanthine dehydrogenase to xanthine oxidase conversion.
Am J Respir Cell Mol Biol 1992 Mar
PMID:Mechanism of neutrophil-induced xanthine dehydrogenase to xanthine oxidase conversion in endothelial cells: evidence of a role for elastase. 154 Mar 91

Sequential polyacrylamide electrophoresis has revealed 20 allozymes of xanthine dehydrogenase (XDH) in Drosophila pseudoobscura. DNA sequence determination of seven isolates of the Xdh locus that represent six allozyme classes are presented here. Of the 5,456 sites examined, 180 are polymorphic, with 27 polymorphisms occurring at nonsynonymous, or replacement, sites. An average of nine amino acids differ between XDH allozyme classes, with 85% of the polymorphic amino acids singly represented. The level and pattern of variation observed at Xdh argue that the effective population size of the species is quite large--i.e., on the order of 2 x 10(6)--and that the populations sampled are quite ancient. In addition, as judged by two statistical tests, the levels of nucleotide polymorphism observed at Xdh are compatible with predictions from the neutral theory of molecular evolution.
Mol Biol Evol 1992 Jan
PMID:Nucleotide polymorphism at the xanthine dehydrogenase locus in Drosophila pseudoobscura. 155 41


1 2 3 4 5 6 7 8 9 Next >>