Synthesis of malate from phosphoenolpyruvate by rabbit liver mitochondria: implications for lipogenesis.
(1) Rabbit liver mitochondria can convert exogenous phosphoenolpyruvate to malate. (2) Malate production is dependent on phosphoenolpyruvate and HCO3- and is stimulated by CN- or malonate alone and especially in combination. (3) Malate production is inhibited 70% by 3-mercaptopicolinate, a specific inhibitor of phosphoenolpyruvate carboxykinase, and 50-60% by 1,2,3-benzenetricarboxylate, an inhibitor of the tricarboxylate transporter. (4) Rat liver mitochondria incubated with phosphoenolpyruvate under identical conditions do not produce malate. (5) Malate production from phosphoenolpyruvate is stimulated by exogenous GDP or IDP but not by ADP. (6) Data support the conclusion that malate is being produced from oxalacetate generated by reversal of mitochondrial phosphoenolpyruvate carboxykinase. A possible role for this enzyme in hepatic lipogenesis is suggested.
Carlsen
B D
BD
Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine, Grand Forks 58202.
Lambeth
D O
DO
Ray
P D
PD
D000818:Animals; D001555:Benzene Derivatives / Q000494:pharmacology; D001639:Bicarbonates / Q000494:pharmacology; D003486:Cyanides / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000494:pharmacology; D007290:Inosine Diphosphate / Q000494:pharmacology; D008055:Lipids / Q000096:biosynthesis*; D008293:Malates / Q000378:metabolism*; D008297:Male; D008314:Malonates / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000378:metabolism*; D009243:NAD / Q000494:pharmacology; D010728:Phosphoenolpyruvate / Q000378:metabolism*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000037:antagonists & inhibitors / Q000378:metabolism; D010848:Picolinic Acids / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D017693:Sodium Bicarbonate; D014233:Tricarboxylic Acids / Q000494:pharmacology
D001555:Benzene Derivatives; D001639:Bicarbonates; D003486:Cyanides; D008055:Lipids; D008293:Malates; D008314:Malonates; D010848:Picolinic Acids; D014233:Tricarboxylic Acids; D009243:NAD; D006153:Guanosine Diphosphate; C004288:benzene 1,2,3-tricarboxylic acid; D010728:Phosphoenolpyruvate; C008363:3-mercaptopicolinic acid; C030298:malic acid; D007290:Inosine Diphosphate; D017693:Sodium Bicarbonate; C030290:malonic acid; D012964:Sodium; D010729:Phosphoenolpyruvate Carboxykinase (GTP)