Integrative Metabolism and Bioenergetics
Oxygen is utilized for the conversion of glucose to pyruvate. The same metabolite also forms from amino acid and protein metabolism. Other precursors like Glycerol, propionate can give rise to pyruvate. The main breakdown product of pyruvate is acetyl CoA, which is the common intermediate in the energy metabolism of carbohydrates, lipid and amino acids. It enters central metabolic pathway, the Citric acid cycle in the mitochondrial matrix. Here it is converted to CO2, H2O and reduced coenzymes (NADH, FADH2). These reduced nucleotides are the substrates for oxidative Phosphorylation in mitochondria, their oxidation provide the energy for the synthesis of ATP, the free energy currency of cells.
