Linked Life Data

6662205

Source:http://linkedlifedata.com/resource/pubmed/id/6662205

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1984-3-23
pubmed:abstractText
Lenses produce both ammonia and urea, and a previous report suggested that bovine lenses contain a complete urea cycle capable of synthesizing urea from bicarbonate and ammonia. To determine whether lenses produce urea by a complete urea cycle or by arginase alone, intact lenses were cultured with [guanido-14C]-arginine or [14C]-bicarbonate. The [14C]-urea was volatilized to [14C]-CO2 by urease and collected in KOH. The cultured rat, bovine and human lenses produced [14C]-urea from [14C]-arginine; therefore lens arginase activity was also examined in homogenates of rat and human lenses. Rat lens homogenates had constant arginase activity for at least 2 hr at 37 degrees C, and activity increased linearly with the concentration of lens homogenate. Rat lens arginase had an apparent Vmax of approximately 13 nmol/hr/mg lens wet weight in lens homogenates and produced 4-6 nmol urea/hr/mg at 25 mM arginine. Human lens homogenates produced 1-5 nmol/hr/mg. In contrast, neither bovine nor rat lenses cultured with [14C]-bicarbonate produced detectable [14C]-urea, although label was incorporated into unidentified nonvolatile products. These products were shown by ion exchange chromatography and enzymatic assay to contain no detectable arginine or urea. It was concluded that although arginase activity is present, neither rat nor bovine lenses contain significant urea cycle activity. However, it is possible that arginase serves as a source of lens ornithine.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0014-4835
pubmed:author
pubmed:issnType
Print
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
551-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Urea formation in rat, bovine, and human lens.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.