Jerusalem artichoke mitochondria can export reducing equivalents in the form of malate as a result of D-lactate uptake and metabolism.
We found that as a result of d-lactate uptake and metabolism by Jerusalem artichoke mitochondria, reducing equivalents were exported from the mitochondrial matrix to the exterior in the form of malate. The rate of malate efflux, as measured photometrically using NADP+ and malic enzyme, depended on the rate of transport across the mitochondrial membrane. It showed saturation characteristics (K(m) = 5 mM; V(max) = 9 nmol/min mg of mitochondrial protein) and was inhibited by non-penetrant compounds. We conclude that reducing equivalent export from mitochondria is due to the occurrence of a putative d-lactate/malate antiporter which differs from other mitochondrial carriers, as shown by the different inhibitor sensitivity.
de Bari
Lidia
L
Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola 165/A, 70126 Bari, Italy.
Valenti
Daniela
D
Pizzuto
Roberto
R
Paventi
Gianluca
G
Atlante
Anna
A
Passarella
Salvatore
S
D006368:Helianthus / Q000378:metabolism* / Q000648:ultrastructure*; D019344:Lactic Acid / Q000378:metabolism*; D008293:Malates / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D019163:Reducing Agents / Q000378:metabolism
D008293:Malates; D019163:Reducing Agents; D019344:Lactic Acid; C030298:malic acid