During gluconeogensis reducing equivalents from mitochondria to cytosol are transported by -

During gluconeogensis reducing equivalents from mitochondria to cytosol are transported by -

    1. Malate
    1. Aspartate
    1. Glutamate
    1. Oxaloacetate

0 voters

ANS

  • Gluconeogenesis is a reversal of glycolytic pathway except for 4 thermodynamic barriers.
  • These 4 energy barriers are :-
  1. Between pyruvate and phosphoenol pyruvate
  2. Between fructose], 6-biphosphate and fructose 6-phosphate
  3. Between glucose 6-phosphate and glucose
  4. Between glucose 1-phosphate and glycogen
  • Reducing equivalents (NADH+H+)are transported from mitochondria to cytosol in overcoming the 1" barrier i.e. ¬≠between pyruvate and phosphoenolpynivate.
  • Conversion of pyruvate to phosphoenolpyruvate is achieved by2 enzymes :-
  1. Pyruvate carboxylase, a mitochondrial enzyme converts pyruvate to oxaloacetate (OAA).
  2. Phosphoenolpyruvate carboxykinase, present chiefly in cytosol, converts OAA to phosphoenolpyruvate.
  • It is noted here that OAA is formed inside the mitochondria but the reaction to convert it into phosphoenol pyruvate occurs in cytosol and OAA is not permeable to mitochondrial membrane.
  • The OAA is transferred to cytosol by 2 mechanisms :-
  1. By formation of Malate
  2. By formation of Citrate
  • The conversion of OAA to Malate and further of Malate to phosphoenol pyruvate is depicted below. The reducing equivalents (NADH+.1-1+) are transferred across the mitochondrial membrane,along with transport of OAA in the form of malate.