Linked Life Data

9870556

Source:http://linkedlifedata.com/resource/pubmed/id/9870556

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
1999-3-16
pubmed:abstractText
Iron containing 3-Hydroxyanthranilate oxidase (3HAO) converts 3-hydroxyanthranilate (3HAA) and dioxygen into a precursor which spontaneously converts to quinolinic acid (QA). 3HAO participates in de novo biosynthesis of NAD in mammalian kidney and liver, and it is present in low concentrations in brain where its function is controversial. However, QA increases in spinal fluid and is associated with convulsions in AIDS dementia, Huntington's disease, and CNS inflammation. QA is a known N-methyl, D-aspartate receptor agonist and excitotoxin that causes convulsions when injected into the brain. Hyperbaric oxygen (HBO) also causes convulsions and we investigated the interrelationships among the stimulating and toxic effects of oxygen and the role of iron in vitro using rat liver enzyme which is reported to be identical to brain enzyme and is more abundant. 3HAO requires dioxygen as a substrate but it was inactivated approximately 40% by 5.2 atm HBO in vitro in 15 min. The apparent Km was 2.6 x 10(-4) M for oxygen and 5 x 10(-5) M for 3HAA, and these values did not change for enzyme that was half-inactivated by HBO oxygen. Thus, oxygen-inactivation appears to be all-or-none for individual enzyme molecules. Freshly prepared enzyme was activated about 3-fold by incubation with acidic iron. Iron-staining of 3HAO, separated by gel electrophoresis after partial purification by FPLC, showed that loss of iron and loss of enzyme activity during HBO exposure were correlated. The apparent oxygen Km of 3HAO is far higher than the oxygen concentration in brain cells. Thus, 3HAO is capable of being stimulated initially in animals breathing HBO, and subsequently of being inactivated with potential significance for brain QA and convulsions.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0891-5849
pubmed:author
pubmed:issnType
Print
pubmed:volume
25
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1033-43
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Effects of oxygen on 3-hydroxyanthranilate oxidase of the kynurenine pathway.
pubmed:affiliation
Dalton Cardiovascular Research Center, University of Missouri, Columbia 65211, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.