Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.17.1.4 (xanthine dehydrogenase)
 1,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The bis(carboxamidomethyl) derivatives of the molybdenum cofactors in three eubacterial molybdo-iron/sulphur-flavoproteins were examined. The quinoline oxidoreductases from Pseudomonas putida 86 and Rhodococcus spec. B1 contain molybdopterin cytosine dinucleotide. In xanthine dehydrogenase from Pseudomonas putida 86, however, only molybdopterin was found. The bis(carboxamidomethyl) derivatives of all three enzymes were treated with nucleotide pyrophosphatase, but only those of the quinoline oxidoreductases were cleaved into [bis(carboxamidomethyl)]molybdopterin and CMP, whereas that of xanthine dehydrogenase remained unchanged. Dephosphorylation by alkaline phosphatase yielded dephospho-[bis(carboxamidomethyl)]molybdopterin and cytidine from the cleaved molybdopterin cytosine dinucleotide. The bis(carboxamidomethyl) derivative from xanthine dehydrogenase was converted to dephospho-[bis(carboxamidomethyl)]molybdopterin by alkaline phosphatase. Acid hydrolysis of the purified enzymes and analysis of the hydrolysate by HPLC confirmed that compared with the xanthine dehydrogenase both quinoline oxidoreductases contain CMP.
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PMID:Microbial metabolism of quinoline and related compounds. X. The molybdopterin cofactors of quinoline oxidoreductases from Pseudomonas putida 86 and Rhodococcus spec. B1 and of xanthine dehydrogenase from Pseudomonas putida 86. 165 36

The molybdenum-containing iron-sulfur flavoprotein xanthine dehydrogenase from the anaerobic bacterium Veillonella atypica has been purified approximately 800-fold with a yield of approximately 40% and a specific activity of approximately 70 micromol ferricyanide reduced x min(-1) x mg protein(-1) with xanthine as electron donor, which corresponds to approximately 30 micromol xanthine oxidized x min(-1) x mg protein(-1) with methylene blue as electron acceptor. The 129-kDa enzyme was a non-covalent heterotrimer with large (82.4 kDa), medium (28.5 kDa) and small (18.4 kDa) subunits. The N-termini of the small and medium polypeptides of V. atypica xanthine dehydrogenase and the corresponding domains of eukaryotic xanthine dehydrogenases were similar, whereas the N-terminus of the large polypeptide was unrelated to eukaryotic xanthine dehydrogenases. The enzyme contained 0.86 atoms Mo, 1.75 atoms Fe, 1.61 atoms acid-labile sulfur and 0.68 molecules FAD/molecule, which corresponds to a 1:2.0:1.9:0.8 molar ratio. Acid hydrolysis revealed 0.95 mol CMP and 0.80 mol AMP/mol xanthine dehydrogenase. After treatment of the enzyme with iodoacetamide, di(carboxamidomethyl)molybdopterin cytosine dinucleotide was identified, which indicates that molybdopterin cytosine dinucleotide is the organic portion of the V. atypica xanthine dehydrogenase molybdenum cofactor. The enzyme and its molybdenum cofactor occurred in a 1:1 molar ratio. Xanthine dehydrogenases from eukaryotic sources are characterized by a domain structure and the presence of duplicate copies of two types of [2Fe-2S) clusters. In contrast, the xanthine dehydrogenase from V. atypica had a heterotrimeric subunit structure and a single [2Fe-2S] cluster. In addition, the enzyme indicates the presence of a molybdopterin dinucleotide as a constituent of a xanthine dehydrogenase molybdenum cofactor.
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PMID:Characterization of xanthine dehydrogenase from the anaerobic bacterium Veillonella atypica and identification of a molybdopterin-cytosine-dinucleotide-containing molybdenum cofactor. 870 91