Xanthine oxidase/dehydrogenase is present in human placenta.
Xanthine dehydrogenase/oxidase (XDH, EC 1.1.1.204, XO, EC 1.2.3.2) produces uric acid, and in the oxidase form also generates the free radical superoxide. Previous reports failed to demonstrate XDH/XO activity in human placenta. Our objective was to determine evidence of XDH/XO in human placenta. We developed a cDNA probe for human XDH/XO and used it to detect mRNA by Northern hybridization. Immunohistochemical localization of the enzyme in placental tissue was performed using a specific antibody for XDH/XO and ABC-peroxidase. Enzyme activity assay was determined by the conversion of [14C] xanthine to [14C] uric acid. mRNA was detected in all placental samples (n = 4). Villous and non-villous trophoblast cells expressed immunohistochemical staining for XOD (n = 4). Enzyme activity was detected in all placentae (n = 6). Despite previous reports, we found mRNA, XDH/XO protein and enzyme activity in human placenta localized to trophoblast cells. Enzyme activity was much lower than in liver. Several conditions in the maternal-fetal unit could potentially increase XDH/XO activity and conversion of the enzyme to its oxidase form.
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Magee Womens Research Institute, Pittsburgh, PA 15213, USA.
Westerhausen-Larson
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Kanbour-Shakir
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Roberts
J M
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D000818:Animals; D015152:Blotting, Northern; D015342:DNA Probes; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D014327:Trophoblasts / Q000201:enzymology; D014527:Uric Acid / Q000378:metabolism; D019820:Xanthine; D014968:Xanthine Dehydrogenase / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D014969:Xanthine Oxidase / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
D015342:DNA Probes; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D014970:Xanthines; D019820:Xanthine; D014527:Uric Acid; D014968:Xanthine Dehydrogenase; D014969:Xanthine Oxidase