Kinetics of the reconstituted dicarboxylate carrier from rat liver mitochondria.
The dicarboxylate carrier from rat liver mitochondria was purified by the Amberlite/hydroxyapatite procedure and reconstituted in egg yolk phospholipid vesicles by removing the detergent with Amberlite. The efficiency of reconstitution was optimized with respect to the ratio of detergent/phospholipid, the concentration of phospholipid and the number of Amberlite column passages. In the reconstituted system the incorporated dicarboxylate carrier catalyzed a first-order reaction of malate/phosphate exchange. V of the reconstituted malate/phosphate exchange was determined to be 6000 mumol/min per g protein at 25 degrees C. This value was independent of the type of substrate present at the external or internal space of the liposomes (malate, phosphate or malonate). The half-saturation constant was 0.49 mM for malate, 0.54 mM for malonate and 1.41 mM for phosphate. The activation energy of the exchange reaction was determined to be 95.8 kJ/mol. The transport was independent of the external pH in the range between pH 6 and 8.
Indiveri
C
C
Department of Pharmaco-Biology, University of Bari, Italy.
Capobianco
L
L
Krämer
R
R
Palmieri
F
F
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008293:Malates / Q000378:metabolism; D008314:Malonates / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D051381:Rats
D002352:Carrier Proteins; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids; D008293:Malates; D008314:Malonates; D010710:Phosphates; C030298:malic acid