Quantitation of the interaction between citrate synthase and malate dehydrogenase.

TitleQuantitation of the interaction between citrate synthase and malate dehydrogenase.
Publication TypeJournal Article
Year of Publication1987
AuthorsTompa, P., J. Batke, J. Ovádi, G. R. Welch, and P. A. Srere
JournalJ Biol Chem
Date Published1987 May 5
KeywordsAdenosine Triphosphate, Animals, Citrate (si)-Synthase, Citrates, Citric Acid, Fluorescence Polarization, Ketoglutaric Acids, Malate Dehydrogenase, Malates, Mitochondria, Heart, NAD, Oxaloacetates, Oxo-Acid-Lyases, Swine

Formation of a bienzyme complex of pig heart mitochondrial malate dehydrogenase and citrate synthase in a buffered system is demonstrated by means of a covalently attached fluorescent probe to citrate synthase. Assuming 1:1 stoichiometry of the enzymes in the complex, an apparent dissociation constant of 10(-6) M was calculated from fluorescence anisotropy measurements. The effect of various metabolites on the interaction was tested. NAD+, oxalacetate, citrate, ATP, and L(-)- or D(+)-malate had no effect on the association of the two enzymes, whereas alpha-ketoglutarate increased and NADH decreased it. The interaction of mitochondrial citrate synthase with cytosolic malate dehydrogenase was found to be much weaker, whereas interaction of citrate synthase with another cytosolic enzyme, aldolase, could not be detected. In kinetic experiments, the activation of malate dehydrogenase by citrate synthase was observed. The effect of pyridine nucleotides and alpha-ketoglutarate is discussed in relation to the direction of the metabolic flow of oxalacetate.

Alternate JournalJ. Biol. Chem.
PubMed ID3571248