Factors affecting L-malate activation of mitochondrial malate dehydrogenase from chicken liver
Dordal, A.; Mazo, A.; Gelpí, J.L.; Cortés, A.
Biochemistry International 20(1): 177-182
1990
ISSN/ISBN: 0158-5231 PMID: 2328021 Document Number: 357301
Mitochondrial malate dehydrogenase is activated by high concentrations of L-malate. In this paper, several factors affecting this activation on chicken liver enzyme have been investigated. The results obtained show clearly that this phenomenon is an intrinsic property of this enzyme since it does not depend on pH or ionic strength of the reaction medium. However, L-malate activation decreases when NAD+ concentration diminishes (5mM----0.2 mM) in such a way that when NAD+ concentration is 0.2 mM, L-malate does not activate mitochondrial malate dehydrogenase. On the other hand, several activators of this enzymatic system, such as citrate or phosphate, also produce the elimination of this activation by L-malate; in this case, the phenomenon seems be due to a competitive binding to a regulatory site of the different metabolites implied.