Hiltunen 1981 Biochim Biophys Acta

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Hiltunen JK, Davis EJ (1981) The disposition of citric acid cycle intermediates by isolated rat heart mitochondria. Biochim Biophys Acta 678:115-21.

» PMID: 7306575

Hiltunen JK, Davis EJ (1981) Biochim Biophys Acta

Abstract: The mechanism of depletion of tricarboxylic acid cycle intermediates by isolated rat heart mitochondria was studied using hydroxymalonate (an inhibitor of malic enzymes) and mercaptopicolinate (an inhibitor of phosphoenolpyruvate carboxykinase) as tools. Hydroxymalonate inhibited the respiration rate of isolated mitochondria in state 3 by 40% when 2 mM malate was the only external substrate, but no inhibition was found with 2 mM malate plus 0.5 mM pyruvate as substrates. In the presence of bicarbonate, arsenite and ATP propionate was converted to pyruvate and malate at the rates of 14.0 ± 2.9 and 2.8 ± 1.8 nmol/mg protein in 5 min, respectively. Under these conditions, 0.1 mM mercaptopicolinate did not affect this conversion, but 2 mM hydroxymalonate inhibited pyruvate formation completely and resulted in an accumulation of malate up to 13.2 ± 2.9 nmol/mg protein. No accumulation of phosphenolpyruvate was found under any condition tested. It is concluded that malic enzymes but not phosphoenolpyruvate carboxykinase, are involved in conversion of propionate to pyruvate in isolated rat heart mitochondria.


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Organism: Rat  Tissue;cell: Heart  Preparation: Isolated mitochondria 


Coupling state: OXPHOS  Pathway:


Malic enzyme