Question

I understand that pyruvate is the result of the breakdown of glucose and is vital to the citric acid cycle and that oxaloacetate is a four-carbon molecule. I was hoping someone could differentiate the two in terms of their overall function and importance to cell processes. How does the cell know which one to use at which time??

Answer 1

Phosphoenol pyruvate - pyruvate- oxaloacetate node involve a structurally entangled set of reactiins that interconnects the major pathway of C - metabolism and thus is responsible for the distribution of C - flux among catabolism, anabolism abd energy supply of the cell. Pyruvate produce in glycolysis that occur in cytosol and produce 2 ATP. In the presence of oxygen, pyruvate converted to acetyl CoA and enter into citric acid cycle that occur in mitochondria. So this process overall called oxidative phosphirylation. Glycolysis continuous occur in cell but TCA cycle occur only when oxygen is present.

Pyruvate involve in catabolism reaction whereas oxaloacetate is a part of anabolic reaction during gluconeogenesis. Intial step of gluconeogenesis established by C3 . phosphoenolpyruvate and C4 oxaloacetate. when glucose concentration is higher, insulin secrete that give signal for break down of glucose in pyruvate and then enter into citric acid cycle. Whereas low glucose concentration lead to secretion of glucagon hormone and oxaloacetate synthesize pyruvate.