Linked Life Data

8620009

Source:http://linkedlifedata.com/resource/pubmed/id/8620009

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1996-6-19
pubmed:abstractText
The approach to steady-state for the formation of the enzyme-carboxybiotin complex obeys first-order kinetics, with the proportion of the total enzyme present as the enzyme-carboxybiotin complex in the steady-state being about 60%. The approach to steady-state for ATP cleavage also obeys first-order kinetics. The apparent first-order rate constants for the approach to steady-state, in the presence and absence of acetyl CoA, respectively, are 6.6 and 0.028 s(-1) for ATP cleavage and 6.1 and 0.028 s(-1) for enzyme-carboxybiotin formation. The similarities of the values of the rate constants for the two reactions indicates that there is a common rate-limiting step. The large enhancement of these rate constants in the presence of acetyl CoA suggests that a major effect of acetyl CoA in the reaction is to enhance the rate of the step in which the putative carboxyphosphate complex is formed and in which ATP is cleaved. In addition, in the presence of acetyl CoA, the formation of the enzyme-carboxybiotin complex is much more tightly coupled to ATP cleavage in the presence of acetyl CoA than in its absence. Modeling studies were performed, and reaction schemes are proposed which give simulations similar to the experimental data. In the reaction schemes, the carboxyphosphate intermediate is able to undergo abortive decomposition without carboxylating biotin. The rate of this abortive reaction is greatly reduced in the presence of acetyl CoA.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3849-56
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Effects of acetyl CoA on the pre-steady-state kinetics of the biotin carboxylation reaction of pyruvate carboxylase.
pubmed:affiliation
Department of Biochemistry, The University of Western Australia, Nedlands, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't