Thus, two molecules of Glyceraldehyde 3-phosphate are obtained from one molecule of Glucose. The enzyme Phosphotriose isomerase catalyzes the reversible interconversion of Glyceraldehyde 3-phosphate and Dihydroxyacetone phosphate.Carbon atoms 4, 5 and 6 appear in glyceraldehyde 3-phosphate and 1, 2 and 3 in dihydroxyacetone phosphate. This reaction is catalyzed by the enzyme Fructose-bisphosphate aldolase (simply called aldolase) which cleaves the Fructose 1, 6-bisphosphate molecule between C 3 and C 4. Fructose 1, 6-bisphosphate is a molecule with phosphate group on both ends, it splits in the middle into two different triose phosphates, Glyceraldehyde 3-phosphate(an aldose) and Dihydroxyacetone phosphate(a ketose) so named as Glycolysis.This is an irreversible and a regulatory step in glycolysis. The enzyme catalyzes the transfer of a phosphate group from ATP to Fructose 6-phosphate at C 1 to yield Fructose 1, 6-bisphosphate. Fructose 6-phosphate is phosphorylated by ATP to produce Fructose 1, 6-bisphosphate in the presence of another inducible allosteric enzyme Phosphofructokinase (PFK).This reaction involves a shift in the carbonyl oxygen from C 1 to C 2, thus converting an aldose into a ketose. Glucose 6-phosphate is reversibly isomerized to Fructose 6-phosphate by Phosphoglucoisomerase in presence of Mg 2+.Glucokinase present in liver catalyzes the phosphorylation of only glucose. The enzyme Hexokinase is present in almost all the lt catalyzes the phosphorylation of various hexose and is inhibited by Glucose 6-phosphate. This is an irreversible reaction, dependent on ATP and Mg 2+. Glucose is phosphorylated at C 6 to yield Glucose 6-phosphate by Hexokinase or Glucokinase (both are isoenzymes).Reactions of Glycolysis: Fig: 10 steps involved in Glycolysisĭuring glycolysis, the 6-carbon glucose is broken down into two moles of 3-carbon pyruvate via 10 enzyme-catalyzed sequential reactions as shown in the above figure. Reversal of glycolysis along with the alternate arrangements at the irreversible steps will result in the synthesis of glucose (gluconeogenesis). Thus, the intermediates of glycolysis are useful for the synthesis of amino acids and fat. Glycolysis is a central metabolic pathway with many of its intermediates providing branch point to other pathways.The glucose in brain has to undergo glycolysis before it is oxidized to CO 2 and H 2O so glycolysis is very essential for the brain which is dependent on glucose for energy.In the aerobic condition, pyruvate is formed, which is then oxidized to CO 2 and H 2O. Lactate is the end product under anaerobic condition. Glycolysis occurs in the absence of oxygen(anaerobic) or in the presence of oxygen (aerobic).It is a major pathway for ATP synthesis in tissues lacking mitochondria, g.The enzymes of this pathway are present in the cytosomal fraction of the cell. It takes place in all cells of the body.Glycolysis is the central pathway of glucose catabolism.The enzymes of this pathway are present in the cytosomal fraction of the of the cell. Glycolysis takes place in all cells of the body.It is frequently referred to as Embden-Meyerhof-Parnas or EMP pathway, in honor of these pioneer workers i.e Gustave Embden(1874-1933), Otto Meyerhof (1883-1951) and Jacob Parnas in the field.lt is a universal pathway in the living.
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