Enzymes of the glycolytic pathway — phosphofructokinase, pyruvate kinase and lactate dehydrogenase

Abstract

Many of the vital reactions in cells, such as the synthesis of biological macromolecules, active transport across membranes and the generation of force and movement, are driven by the energy provided by the hydrolysis of ATP. Glucose is the principal food compound of many cells for the ATP production. By a sequence of reactions termed glycolysis, a glucose molecule with six carbon atoms is converted to two pyruvate molecules each with three carbon atoms, and finally two ATP molecules are produced. For most animal cells, glycolysis is only a prelude to subsequent reaction steps that occur in mitochondria: under aerobic conditions, one pyruvate molecule is eventually broken down into three carbon dioxide and three water molecules through the citric acid cycle (tricarboxylic acid cycle or Krebs cycle) and oxidative phosphorylation, yielding far more ATP molecules. Although the generation of ATP through glycolysis is relatively inefficient, it is the most fundamental and important pathway because: (a) it is the predominant and only metabolic pathway from glucose to pyruvate which can then be catabolized in the TCA cycle; (b) it produces ATP even in the absence of oxygen; and (c) it produces intermediates needed for the synthesis of fundamental biological materials such as amino acids and fatty acids.