Pyruvate Dehydrogenase Complex from Higher Plant Mitochondria and Proplastids: Regulation 1
AUTOR(ES)
Thompson, Paul
RESUMO
The activity of the pyruvate dehydrogenase complex from pea (Pisum sativum L.) mitochondria is inhibited when MgATP is added to the reaction mixture; 50% inhibition occurs at 4 mm ATP. The inhibition does not increase with time and is higher in the more highly purified preparations. Crude preparations of the complex show a time-dependent inactivation when incubated with 7.5 mm MgATP alone but this is not found with the more highly purified complex. This inactivation does not occur at 0 C. The complex could not be reactivated by high concentrations of Mg2+. It is suggested that a phosphorylation-dephosphorylation mechanism may occur in plants, but the phosphatase and kinase are not tightly bound to the complex and are lost on isolation. The complex does not respond in a significant manner to energy charge. The NAD+ to NADH ratio is the principal means of regulation of the complex, NADH being competitive with NAD+ for the dihydrolipoamide component. The CoA to acetyl-CoA ratio is not important in regulation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=543309Documentos Relacionados
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