Stimulation of citrate oxidation and transport in human placental mitochondria by L-malate.
1. Citrate was oxidized by human placental mitochondria at a rate half that for isocitrate, and cis-aconitate at a rate by 20% lower as with isocitrate. The apparent Km values for these substrates were similar. 2. Oxidation of citrate was stimulated by L-malate but the stimulation was abolished by benzene 1,2,3-tricarboxylate and butylmalonate. 3. Citrate uptake by placental mitochondria was inhibited by benzene 1,2,3--tricarboxylate, and raised specifically by L-malate. Stimulation by fumarate and succinate was found to be due to conversion of these substrates to L-malate. 4. It is concluded that human placental mitochondria contain malate-stimulated tricarboxylate carrier system.
D000156:Aconitic Acid / Q000378:metabolism; D002951:Citrates / Q000378:metabolism*; D002952:Citric Acid Cycle; D005260:Female; D005650:Fumarates / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007523:Isocitrates / Q000378:metabolism; D007700:Kinetics; D008293:Malates / Q000494:pharmacology*; D008314:Malonates / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013386:Succinates / Q000494:pharmacology; D014233:Tricarboxylic Acids / Q000378:metabolism
D002951:Citrates; D005650:Fumarates; D007523:Isocitrates; D008293:Malates; D008314:Malonates; D013386:Succinates; D014233:Tricarboxylic Acids; D000156:Aconitic Acid