Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a 3-week old female child with clinical features including neurologic abnormalities and lens dislocation, xanthinuria co-existed with increased excretion of sulfur compounds (sulfite, S-sulfocysteine, taurine and thio-sulfate). Low xanthine oxidase and absent sulfite oxidase activities were found on liver biopsy. No abnormality was detected in either parent. Both the above enzymes are molybdenum-flavoproteins. Normal serum molybdenum concentration seemed to rule out dietary deficiency or impaired absorption. A defect in the incorporation of the metal into flavoproteins is postulated in this case.
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PMID:Simultaneous occurrence of xanthine oxidase and sulfite oxidase deficiency. A molybdenum dependent inborn error of metabolism? 58 2

Frozen liver tissue from an individual identified several years ago as sulfite oxidase deficient has been reexamined in light of new knowledge which has been obtained regarding the enzyme. It has been established that hepatic molybdenum levels and xanthine oxidase activity were within normal values and comparable to those observed in control samples preserved from the original study along with the deficient tissue sample. The ability of the patient's liver to synthesize the specific molybdenum cofactor required for activation of de-molybdo sulfite oxidase also appears to have been unimpaired. Using an antibody preparation directed against rat liver sulfite oxidase which also inhibits and precipitates the human enzyme, it has been determined that cross-reacting material with determinants recognized by inhibiting antibodies is absent in the liver sample from the deficient patient. Immunodiffusion experiments gave strong precipitin bands against the control liver extracts, but showed no detectable precipitin reaction between the deficient liver extract and the antibody preparation. The relationship of these findings to a second patient recently identified as sulfite oxidase deficient and to an animal model of the disease are discussed.
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PMID:Human sulfite oxidase deficiency. Characterization of the molecular defect in a multicomponent system. 95 84

A simple and reliable procedure of oxidation of molybdenum cofactor (MoCo) from molybdoenzymes by autoclaving samples at 120 degrees C for 20 min yielded a single predominant fluorescent species that could be quantitatively determined by reverse phase high performance liquid chromatography. This method allowed detection and quantitation of molybdopterin in cell-free extracts of the green alga Chlamydomonas reinhardtii. The MoCo oxidation product from C. reinhardtii has the same chromatographic and spectral properties as that of milk xanthine oxidase and chicken liver sulfite oxidase. The oxidized species was also detected in molybdenum cofactor mutants of Chlamydomonas reinhardtii defective at the nit-3, nit-4, nit-5/nit-6 and nit-7 loci, which strongly suggests that active molybdenum cofactor itself is not directly involved in the control of its own biosynthetic pathway.
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PMID:Quantitation of molybdopterin oxidation product in wild-type and molybdenum cofactor deficient mutants of Chlamydomonas reinhardtii. 147 98

Sixty 3-wk-old female Sprague-Dawley rats were randomly divided into six groups of 10 animals each. Group 1 was fed for 8 wk purified AIN-76A diet (basal diet) containing 0.025 mg molybdenum/kg diet. Groups 2-6 were fed the same basal diet supplemented with sodium molybdate to provide total dietary Mo of 0.050, 0.100, 0.200, 0.400 and 0.800 mg/kg diet, respectively. Molybdenum concentration in liver and brain increased linearly up to the 0.200 mg Mo/kg diet level. Beyond this level, no further significant increase occurred. Dietary Mo of 0.100 mg/kg elevated the Mo concentration in heart to its maximal level. Supplementation with 0.025 mg Mo/kg to a total of 0.05 mg Mo/kg diet significantly increased Mo concentration in spleen and kidney; higher levels of dietary Mo did not result in further significant responses. Molybdenum supplementation significantly increased the activities of xanthine dehydrogenase/oxidase (XDH), sulfite oxidase and superoxide dismutase in the liver, and of XDH in small intestinal mucosa. Maximal activities were attained at 0.050, 0.050, 0.200 and 0.100 mg Mo/kg diet, respectively. Dietary Mo of 0.200 mg/kg diet was estimated as the Mo requirement of rats fed the AIN-76A diet.
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PMID:Molybdenum requirement of female rats. 155 58

Molybdenum is an essential trace element taking part in the active site of three human enzymes: xanthine oxidase, aldehyde oxidase and sulfite oxidase, playing a role in the detoxification of the organism and/or the production of important intermediary products. The perturbation of the first two enzymes has no established clinical consequence, but a decrease in activity of the third one is harmful for the organism, particularly the nervous system during pre- or post-natal development. The anomalies in the function of these enzymes are generally inherited and linked to the impaired production of the molybdenum cofactor, an organic molecule complexed to the element in the active site. However, several pathological cases in animals and one case in man have been clearly attributed to molybdenum deficiency. It is the reason why molybdenum supplementation has been recommended in long term total parenteral nutrition in infants and adults.
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PMID:[The nutritional importance and physiopathology of molybdenum in man]. 175 80

31P ENDOR spectra are described for three different molybdenum(V) species in reduced xanthine oxidase samples. The spectra were not affected by removing the FAD from the enzyme, implying that this is located at some distance from molybdenum. Furthermore, in confirmation of the work of J. L. Johnson, R. E. London, and K. V. Rajagopalan [(1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6493-6497], NMR and chemical analysis of the phosphate content of highly purified xanthine oxidase showed there are only three phosphate residues per subunit of the enzyme. It is concluded that the ENDOR features are due to hyperfine coupling of the phosphate group of the pterin cofactor to the molybdenum atom. Evaluation of the dipolar component of the coupling has permitted estimation of the molybdenum-phosphorus distances as 7-12 A. This implies that the cofactor is in an extended conformation in the enzyme molecule. Less detailed 31P ENDOR data on sulfite oxidase are consistent with a similar conformation for the cofactor in this enzyme.
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PMID:31P ENDOR studies of xanthine oxidase: coupling of phosphorus of the pterin cofactor to molybdenum (V). 185 Feb 96

The nature of molybdenum cofactor in the bacterial enzyme dimethyl sulfoxide reductase has been investigated by application of alkylation conditions that convert the molybdenum cofactor in chicken liver sulfite oxidase and milk xanthine oxidase to the stable, well-characterized derivative [di(carboxamidomethyl)]molybdopterin. The alkylated pterin obtained from dimethyl sulfoxide reductase was shown to be a modified form of alkylated molybdopterin with increased absorption in the 250-nm region of the spectrum and altered chromatographic behavior. The complex alkylated pterin was resolved into two components by treatment with nucleotide pyrophosphatase. These were identified as di(carboxamidomethyl)molybdopterin and GMP by their absorption spectra, coelution with standard compounds, and by further degradation by alkaline phosphatase to dephospho [di(carboxamidomethyl)]molybdopterin and guanosine. The GMP moiety was sensitive to periodate, identifying it as the 5' isomer. Chemical analysis of the intact alkylated pterin showed the presence of two phosphate residues per pterin. These results established that the pterin isolated from dimethyl sulfoxide reductase contains the phosphoric anhydride of molybdopterin and 5'-GMP, which is designated molybdopterin guanine dinucleotide.
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PMID:Molybdopterin guanine dinucleotide: a modified form of molybdopterin identified in the molybdenum cofactor of dimethyl sulfoxide reductase from Rhodobacter sphaeroides forma specialis denitrificans. 232 78

Methods have been devised to examine the spectral properties and state of reduction of the pterin ring of molybdopterin (MPT) in milk xanthine oxidase and the Mo-containing domain of rat liver sulfite oxidase. The absorption spectrum of the native pterin was visualized by difference spectroscopy of each protein, denatured anaerobically in 6 M guanidine hydrochloride (GdnHCl), versus a sample containing the respective apoprotein and other necessary components. The state of reduction of MPT was also probed using 2,6-dichlorobenzenoneindophenol (DCIP) to measure reducing equivalents/MPT, after anaerobic denaturation of the protein in GdnHCl in the presence or absence of Hg2+. In the case of xanthine oxidase the data indicate that the terminal sulfide ligand of Mo causes the reduction of a native dihydro form of MPT to the tetrahydro level. This reduction does not occur if Hg2+ is added prior to denaturation of the protein. Based on its observed behavior, the native MPT in the Mo cofactor of xanthine oxidase is postulated to exist as a quinonoid dihydropterin. Quantitation of DCIP reduction by MPT of Mo fragment of sulfite oxidase showed a two-electron oxidation of MPT, even when the Mo fragment was denatured in the presence of Hg2+ to prevent internal reduction reactions due to sulfhydryls or sulfide. Difference spectra of DCIP-treated versus untreated Mo fragment showed that MPT had been fully oxidized. These data indicate that the native MPT in sulfite oxidase must be a dihydro isomer different from that in xanthine oxidase.
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PMID:The state of reduction of molybdopterin in xanthine oxidase and sulfite oxidase. 237 87

Cytochrome a1c1 (nitrite-cytochrome c oxidoreductase) purified from Nitrobacter winogradskyi (formerly N. agilis) contained molybdenum, non-heme iron, and acid-labile sulfur in addition to hemes a and c; it contained 1 mol of heme a, 4-5 g atoms of non-heme iron, 2-5 g atoms of acid-labile sulfur, and 1-2 g atoms of molybdenum per mol of heme c, but did not contain copper. The fluorescence spectra of the molybdenum cofactor derivative prepared from cytochrome a1c1 were very similar to those of the cofactor derivative from xanthine oxidase, and the aponitrate reductase of nit-1 mutant of Neurospora crassa was complemented by addition of the molybdenum cofactor derived from the cytochrome. Further, the ESR spectrum of cytochrome a1c1 was similar to that of liver sulfite oxidase. The content of cytochrome a1 in the cells cultivated with the medium in which tungsten was substituted for molybdenum markedly decreased as compared with that in the cells cultivated in the molybdenum-supplemented medium. These results indicate that cytochrome a1c1 is an iron-sulfur molybdoenzyme which contains hemes a and c.
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PMID:Nitrobacter winogradskyi cytochrome a1c1 is an iron-sulfur molybdoenzyme having hemes a and c. 282 43

The effects of molybdenum (Mo) supplementation in the drinking water at the levels of 0.1, 0.5, 1.0, 2.0, 5.0 and 10.0 mg/l on the hepatic trace element concentrations and enzyme activities of female Sprague-Dawley rats were studied. The mean hepatic Mo concentration increased significantly in the rats supplemented with 0.1 mg Mo/l as compared to the nonsupplemented rats, but a further significant increase did not occur until the supplementation level reached 5-10 mg Mo/l drinking water. Hepatic copper concentration of the group given 0.1 mg Mo/l and hepatic iron content of the groups given 0.1 or 0.5 mg Mo/l were significantly higher than those of the other groups. The hepatic xanthine dehydrogenase/oxidase activity was not significantly affected by Mo supplementation. The hepatic sulfite oxidase (SOX) activity of the group given 0.1 mg Mo/l was significantly higher than that of the nonsupplemented group. The SOX activities of all the other supplemented groups were at a significantly different level intermediate between the first two. The hepatic superoxide dismutase (SOD) activity was significantly higher in the group given 0.1 mg/l than in the other groups. These results indicated that molybdenum enzymes and SOD might not be participants in previously reported anticarcinogenic activity of Mo, as supplementation at the level of 0.1 mg/l had been observed to be inefficacious in inhibiting N-nitrosomethylurea-induced mammary tumor incidence.
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PMID:Effect of molybdenum supplementation on hepatic trace elements and enzymes of female rats. 291 95


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