Linked Life Data

17451884

Source:http://linkedlifedata.com/resource/pubmed/id/17451884

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2007-5-8
pubmed:abstractText
The lyase activity toward Se-methylated selenoamino acids and the demethylase activity toward methylselenol in the metabolism of selenium were characterized in vitro. The beta- and gamma-lyase activities toward selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys), respectively, were compared under exactly identical conditions by incubating 77Se-SeMet and 76Se-MeSeCys simultaneously in a liver supernatant, and then estimated by the decreases in the labeled starting selenoamino acids (MeSeCys and SeMet), and also by the increases in the labeled enzyme products (methylselenol and selenide) after oxidation to methylseleninic acid (MSA(IV)) and selenite, respectively, by HPLC-inductively coupled plasma-mass spectrometry (ICP-MS). Only 76Se-MeSeCys was decreased and only 76Se-selenite was produced, suggesting that conversion of MeSeCys to methylselenol by beta-lyase followed by that of methylselenol to selenide by demethylase actively occurred in the liver supernatant. The demethylase activity was characterized by incubating 77Se-methylselenol produced in situ from 77Se-MSA(IV) and glutathione in a partially purified enzyme preparation. It was found that demethylation takes place directly through an attack by a hydroxide anion on the methyl group of methylselenol producing selenide and methanol, selenide being detected on HPLC-ICP-MS after oxidation to selenite, and methanol on GC-MS. It was concluded that beta- but not gamma-lyase activity could be detected in a liver supernatant, and that the resulting methylselenol product is demethylated through hydrolysis, with methanol and selenide being produced (MeSeCys-->CH3SeH-->HSeH + CH3OH).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:volume
1770
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1053-61
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Selenocysteine beta-lyase and methylselenol demethylase in the metabolism of Se-methylated selenocompounds into selenide.
pubmed:affiliation
Graduate School of Pharmaceutical Sciences, Chiba University, Chuo, Chiba 260-8675, Japan. ktsuzuki@p.chiba-u.ac.jp
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't