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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The action of some known and new synthesized substituted 1,2,3-triazoles on adenosine deaminase, guanine deaminase and xanthine oxidase was studied. The effect of substituents in 1, 4 and 5 positions was studied and discussed. The presence of a carboxamido group in 4 position seems to be essential in the binding to adenosine deaminase.
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PMID:Effects of substituted 1,2,3-triazoles on adenosine deaminase, guanine deaminase and xanthine oxidase. 58 99

Six 2-methyl-3-substituted-pyrido-(2,3-d)-pyrimidine 4 (3H)-ones were synthesized and evaluated for their ability to inhibit xanthine oxidase and other purine catabolizing enzymes of rat liver. All compounds inhibited xanthine oxidase selectively when tested at a final concentration of 0.5 mM in vitro. Adenosine deaminase, guanosine deaminase and guanine deaminase were unaffected. The inhibition of xanthine oxidase was found to be competitive in nature.
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PMID:Selective inhibition of xanthine oxidase by substituted pyridopyrimidines. 68 70

Purine nucleotide synthesis and interconversion were examined over a range of purine base and nucleoside concentrations in intact N4 and N4TG (hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficient) neuroblastoma cells. Adenosine was a better nucleotide precursor than adenine, hypoxanthine or guanine at concentrations greater than 100 micron. With hypoxanthine or guanine, N4TG cells had less than 2% the rate of nucleotide synthesis of N4 cells. At substrate concentrations greater than 100 micron the rates for deamination of adenosine and phosphorolysis of guanosine exceeded those for any reaction of nucleotide synthesis. Labelled inosine and guanosine accumulated from hypoxanthine and guanine, respectively, in HGPRT-deficient cells and the nucleosides accumulated to a greater extent in N4 cells indicating dephosphorylation of newly synthesized IMP and GMP to be quantitatively significant. A deficiency of xanthine oxidase, guanine deaminase and guanosine kinase activities was found in neuroblastoma cells. Hypoxanthine was a source for both adenine and guanine nucleotides, whereas adenine or guanine were principally sources for adenine (greater than 85%) or guanine (greater than 90%) nucleotides, respectively. The rate of [14C]formate incorporation into ATP, GTP and nucleic acid purines was essentially equivalent for both N4 and N4TG cells. Purine nucleotide pools were also comparable in both cell lines, but the concentration of UDP-sugars was 1.5 times greater in N4TG than N4 cells.
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PMID:A comparison of purine metabolism and nucleotide pools in normal and hypoxanthine-guanine phosphoribosyltransferase-deficient neuroblastoma cells. 71 89

A comprehensive study on enzyme ligand interactions by QSAR techniques is discussed. Thirteen correlation equations are presented which relate activity of 1086 ligands of isolated chloroplasts, chymotrypsin, dihydrofolate reductase, xanthine oxidase and guanine deaminase to their chemical structures. Two kinds of space within and on the surface of an enzyme are defined by means of pi and MR constants. Emphasis is put on the use of indicator variables as a means of rationalizing special enzyme-ligand interactions. The use of such studies for drug development is discussed.
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PMID:[Correlative analysis in the study of enzyme-ligand interactions]. 73 55

Five correlation equations are presented which relate inhibitory activity of 578 inhibitors of guanine deaminase, xanthine oxidase, dihydrofolate reductase, and complement to their chemical structures. The use of correlation analysis in enzyme studies for drug development is discussed. The importance of indicator variables in such studies is emphasized.
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PMID:Correlation analysis of Baker's studies on enzyme inhibition. 1. Guanine deaminase, xanthine oxidase, dihydrofolate reductase, and complement. 124 55

Erythrocytes of five strains of mice had ATP concentrations of ca 2.7 mumol/ml packed cells, while those of CBA mice were 23% lower, and those of BALB/C mice were 40% lower. The ratio of the concentrations of ATP and GTP were ca 3.3 in four strains but greater than 27 in three other strains. When erythrocytes from different mouse strains were incubated with radioactive precursors, appreciable strain differences were found in the apparent activities of adenine and hypoxanthine-guanine phosphoribosyltransferase, adenosine kinase, adenosine deaminase, guanine deaminase and xanthine oxidase. The activities of adenosine deaminase and guanine deaminase in sera of mice of different strains also varied.
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PMID:Variation in erythrocyte purine metabolism among mouse strains. 668 81

We describe an enzymic, one-step kinetic method for determination of guanine deaminase (guanase, EC 3.5.4.3) in serum with a centrifugal analyzer. A combined enzyme-substrate system consists of the enzymes xanthine oxidase, catalase, and aldehyde dehydrogenase, the coenzyme NAD+, the substrate guanine, and ethanol in tris(hydroxymethyl)methylamine buffer, with KCl added as activator for aldehyde dehydrogenase. The method requires only 40 microL of sample. Guanase activity in 28 samples can be determined within 10 min by setting a 4-min lag period. The increase in absorbance at 340 nm is linearly proportional to the activity of guanase to 60 U/L. Within-run precision (CV) was 1.32 to 4.50% over the range studied. Day-to-day precision corresponds to CVs of 4.8 to 7.2% over the same range of guanase activity. The reference interval, as calculated from data on 25 healthy humans, was 0 to 1.02 U/L. The enzymic automated method shows good correlation with Caraway's (Clin. Chem. 12: 187, 1966) method (r = 0.949).
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PMID:Kinetic measurement of guanine deaminase in serum with a centrifugal analyzer. 747 21

Among progeny of a hybrid (Rana shqiperica x R. lessonae) x R. lessonae, 14 of 22 loci form four linkage groups (LGs): (1) mitochondrial aspartate aminotransferase, carbonate dehydratase-2, esterase 4, peptidase D; (2) mannosephosphate isomerase, lactate dehydrogenase-B, sex, hexokinase-1, peptidase B; (3) albumin, fructose-biphosphatase-1, guanine deaminase; (4) mitochondrial superoxide dismutase, cytosolic malic enzyme, xanthine oxidase. Fructose-biphosphate aldolase-2 and cytosolic aspartate aminotransferase possibly form a fifth LG. Mitochondrial aconitate hydratase, alpha-glucosidase, glyceraldehyde-3-phosphate dehydrogenase, phosphogluconate dehydrogenase, and phosphoglucomutase-2 are unlinked to other loci. All testable linkages (among eight loci of LGs 1, 2, 3, and 4) are shared with eastern palearctic water frogs. Including published data, 44 protein loci can be assigned to 10 of the 13 chromosomes in Holarctic Rana. Of testable pairs among 18 protein loci, agreement between Palearctic and Nearctic Rana is complete (125 unlinked, 14 linked pairs among 14 loci of five syntenies), and Holarctic Rana and Xenopus laevis are highly concordant (125 shared nonlinkages, 13 shared linkages, three differences). Several Rana syntenies occur in mammals and fish. Many syntenies apparently have persisted for 60-140 x 10(6) years (frogs), some even for 350-400 x 10(6) years (mammals and teleosts).
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PMID:Linkage groups of protein-coding genes in western palearctic water frogs reveal extensive evolutionary conservation. 928 85

The activities of purine salvage enzymes in tachyzoites from a cyst-forming strain of Toxoplasma gondii were determined using HPLC. Six enzymes were assayed both in vitro and in vivo: adenosine deaminase, guanine deaminase, purine nucleoside phosphorylase, xanthine oxidase, hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase. In vitro, the tachyzoites were cultured in the human myelomonocytic cell line THP-1, for 24 h to 96 h. Neither guanine deaminase nor hypoxanthine-guanine phosphoribosyltransferase activity was detected in 24 and 96 h cultures. In vivo, in controls and infected animals, the purine nucleoside phosphorylase and adenosine deaminase activities were the most important activities both in sera and cerebral tissue in comparison with the other activities. It was also noted that the infection modified the enzymatic activities of this purine salvage pathway, in particular, the guanine deaminase cerebral activity of infected mice was 20-fold lower than the value of controls. The treatment of mice with 2',3'-dideoxyinosine, a purine analog, at the dose of 100 mg.kg(-1).d for 30 days, induced an important increase of all enzymatic activities in the brains in comparison with control animals. These data suggest that one target of 2',3'-dideoxyinosine is the purine metabolism.
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PMID:Purine pathway enzymes in a cyst forming strain of Toxoplasma gondii. 1057 52

The purine analogue, allopurinol, has been in clinical use for more than 30 years as an inhibitor of xanthine oxidase (XO) in the treatment of hyperuricemia and gout. As consequences of structural similarities to purine compounds, however, allopurinol, its major active product, oxypurinol, and their respective metabolites inhibit other enzymes involved in purine and pyrimidine metabolism. Febuxostat (TEI-6720, TMX-67) is a potent, non-purine inhibitor of XO, currently under clinical evaluation for the treatment of hyperuricemia and gout. In this study, we investigated the effects of febuxostat on several enzymes in purine and pyrimidine metabolism and characterized the mechanism of febuxostat inhibition of XO activity. Febuxostat displayed potent mixed-type inhibition of the activity of purified bovine milk XO, with Ki and Ki' values of 0.6 and 3.1 nM respectively, indicating inhibition of both the oxidized and reduced forms of XO. In contrast, at concentrations up to 100 muM, febuxostat had no significant effects on the activities of the following enzymes of purine and pyrimidine metabolism: guanine deaminase, hypoxanthine-guanine phosphoribosyltransferase, purine nucleoside phosphorylase, orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase. These results demonstrate that febuxostat is a potent non-purine, selective inhibitor of XO, and could be useful for the treatment of hyperuricemia and gout.
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PMID:Selectivity of febuxostat, a novel non-purine inhibitor of xanthine oxidase/xanthine dehydrogenase. 1569 61


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