Linked Life Data

11383136

Source:http://linkedlifedata.com/resource/pubmed/id/11383136

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2001-5-31
pubmed:abstractText
Xanthine oxidase (XO) has been investigated for its decreased activity in several cancerous tissues and constitutive generation of reactive oxygen species (ROS) in vivo seems to contribute significantly to its inactivation. Singlet oxygen (1O2) production has been suggested to be relevant when considering folic acid metabolism by cancer cells. Thus, the susceptibility of XO to inactivation by 1O2 generated either by the bioenergized systems folic acid/peroxidase/GSH/Mn2+/O2 and malonaldehyde/peroxidase/Mn2+/O2 or by methylene blue (MB) or eosin-sensitized photooxygenation was studied. Our results showed that other ROS were also responsible for XO inactivation when MB was used. In contrast, eosin produced almost exclusively 1O2. Kinetic studies of XO oxidation in the malonaldehyde/peroxidase system showed that histidine (His) is a competitive inhibitor with respect to XO. A similar result was observed in the eosin-photosensitized process, suggesting the involvement of 1O2 in both processes. In addition, an efficient quenching of XO oxidation by guanosine in the folic acid/peroxidase system was observed. Amino acid analysis revealed that cysteine (Cys) is more affected than other XO amino acids also prone to oxidation such as tyrosine (Tyr), methionine (Met) and His. These results indicate that 1O2 may cause oxidative damage to the Cys residues of XO, with loss of enzyme activity. Alteration of the flavin prosthetic site is hypothesized.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0748-6642
pubmed:author
pubmed:issnType
Print
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
145-54
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Sensitized photooxygenation and peroxidase-catalyzed inactivation of xanthine oxidase--evidence of cysteine damage by singlet oxygen.
pubmed:affiliation
Instituto de Química, Biological Chemistry Laboratory, Universidade Estadual de Campinas (Unicamp), C.P. 6154, CEP 13083-970, Campinas, S.P., Brazil.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't