Linked Life Data

9540805

Source:http://linkedlifedata.com/resource/pubmed/id/9540805

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-5-4
pubmed:abstractText
Ornithine transcarbamylase (OTCase) catalyzes the reaction between L-ornithine and carbamyl phosphate in the first step of the urea cycle. 13C isotope effects were measured in carbamyl phosphate, using OTCase obtained from E. coli in a one-column purification which yielded 30 mg of very pure enzyme from 51 of cell culture. At near zero L-ornithine, the 13C kinetic isotope effect was 1.0095, at high levels of L-ornithine (86 mM) the 13C kinetic isotope effect was unity, and 0.83 mM ornithine was found to eliminate half the isotope effect. These results are indicative of an ordered kinetic mechanism in which carbamyl phosphate binds to the enzyme before L-ornithine. Similar experiments were performed using the slow substrate L-lysine in place of L-ornithine. At 90 mM L-lysine the 13C kinetic isotope effect was large, 1.076. This value is most likely the intrinsic kinetic isotope effect with this substrate, and the chemistry of the enzyme catalyzed reaction has become rate limiting.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
1382
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
333-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Studies on the urea cycle enzyme ornithine transcarbamylase using heavy atom isotope effects.
pubmed:affiliation
Department of Chemistry, Beloit College, WI 53511, USA. parmentr@beloit.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.