Linked Life Data

15448145

Source:http://linkedlifedata.com/resource/pubmed/id/15448145

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
50
pubmed:dateCreated
2004-12-6
pubmed:abstractText
Xanthine oxidase is generally recognized as a key enzyme in purine catabolism, but its structural complexity, low substrate specificity, and specialized tissue distribution suggest other functions that remain to be fully identified. The potential of xanthine oxidase to generate superoxide radical anion, hydrogen peroxide, and peroxynitrite has been extensively explored in pathophysiological contexts. Here we demonstrate that xanthine oxidase turnover at physiological pH produces a strong one-electron oxidant, the carbonate radical anion. The radical was shown to be produced from acetaldehyde oxidation by xanthine oxidase in the presence of catalase and bicarbonate on the basis of several lines of evidence such as oxidation of both dihydrorhodamine 123 and 5,5-dimethyl-1-pyrroline-N-oxide and chemiluminescence and isotope labeling/mass spectrometry studies. In the case of xanthine oxidase acting upon xanthine and hypoxanthine as substrates, carbonate radical anion production was also evidenced by the oxidation of 5,5-dimethyl-1-pyrroline-N-oxide and of dihydrorhodamine 123 in the presence of uricase. The results indicated that Fenton chemistry occurring in the bulk solution is not necessary for carbonate radical anion production. Under the conditions employed, the radical was likely to be produced at the enzyme active site by reduction of a peroxymonocarbonate intermediate whose formation and reduction is facilitated by the many xanthine oxidase redox centers. In addition to indicating that the carbonate radical anion may be an important mediator of the pathophysiological effects of xanthine oxidase, the results emphasize the potential of the bicarbonate-carbon dioxide pair as a source of biological oxidants.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
51836-43
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Production of the carbonate radical anion during xanthine oxidase turnover in the presence of bicarbonate.
pubmed:affiliation
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Caixa Postal 26077, São Paulo CEP 05513-970, Brazil.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't