Linked Life Data

6712621

Source:http://linkedlifedata.com/resource/pubmed/id/6712621

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1984-5-10
pubmed:abstractText
The degree of inhibition of CPT I (carnitine palmitoyltransferase, EC 2.3.1.21) in isolated rat liver mitochondria by malonyl-CoA was studied by measuring the activity of the enzyme over a short period (15s) after exposure of the mitochondria to malonyl-CoA for different lengths of time. Inhibition of CPT I by malonyl-CoA was markedly time-dependent, and the increase occurred at the same rate in the presence or absence of palmitoyl-CoA (80 microM), and in the presence of carnitine, such that the time-course of acylcarnitine formation deviated markedly from linearity when CPT I activity was measured in the presence of malonyl-CoA over several minutes. The initial rate of increase in degree of inhibition with time was independent of malonyl-CoA concentration. CPT I in mitochondria from 48 h-starved rats had a lower degree of inhibition by malonyl-CoA at zero time, but was equally capable of being sensitized to malonyl-CoA, as judged by an initial rate of increase of inhibition identical with that of the enzyme in mitochondria from fed rats. Double-reciprocal plots for the degree of inhibition produced by different malonyl-CoA concentrations at zero time for the enzyme in mitochondria from fed or starved animals indicated that the enzyme in the latter mitochondria was predominantly in a state with low affinity for malonyl-CoA (concentration required to give 50% inhibition, I0.5 congruent to 10 microM), whereas that in mitochondria from fed rats displayed two distinct sets of affinities: low (congruent to 10 microM) and high (less than 0.3 microM). Plots for mitochondria after incubation for 0.5 or 1 min with malonyl-CoA indicated that the increased sensitivity observed with time was due to a gradual increase in the high-affinity state in both types of mitochondria. These results suggest that the sensitivity of CPT I in rat liver mitochondria in vitro had two components: (i) an instantaneous sensitivity inherent to the enzyme which depends on the nutritional state of the animal from which the mitochondria are isolated, and (ii) a slow, malonyl-CoA-induced, time-dependent increase in sensitivity. It is suggested that the rate of malonyl-CoA-induced sensitization of the enzyme to malonyl-CoA inhibition is limited by a slow first-order process, which occurs after the primary event of interaction of malonyl-CoA with the mitochondria.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-4638549, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-6860680, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-6870813, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-6882381, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-6997308, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-7126192, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-7165725, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-7297689, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-7326003, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-7470052, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-863933, http://linkedlifedata.com/resource/pubmed/commentcorrection/6712621-991860
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0264-6021
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
218
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
379-86
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Time-dependence of inhibition of carnitine palmitoyltransferase I by malonyl-CoA in mitochondria isolated from livers of fed or starved rats. Evidence for transition of the enzyme between states of low and high affinity for malonyl-CoA.
pubmed:publicationType
Journal Article, In Vitro