Chapter 15 Glycolysis and the catabolism of Hexoses
Chapter 15 Glycolysis and the Catabolism of Hexoses
An overview on D-glucose metabolism The major fuel of most organisms, G0=2840 kJ/mole if completely oxidized to co2 and h,o via the glycolysis pathway, citric acid cycle and oxidative phosphorylation (generating ATP) Can also be oxidized to make nadph and ribose-5-P via the pentose phosphate pathway Can be stored in polymer form(glycogen or starch) or be converted to fat for long term storage Is also a versatile precursor for carbon skeletons of almost all kinds of biomolecules, including amino acids nucleotides, fatty acids, coenzymes and other metabolic intermediates
An overview on D-glucose metabolism • The major fuel of most organisms, G' o = –2840 kJ/mole if completely oxidized to CO2 and H2O via the glycolysis pathway, citric acid cycle and oxidative phosphorylation (generating ATP) . • Can also be oxidized to make NADPH and ribose-5-P via the pentose phosphate pathway. • Can be stored in polymer form (glycogen or starch) or be converted to fat for long term storage. • Is also a versatile precursor for carbon skeletons of almost all kinds of biomolecules, including amino acids, nucleotides, fatty acids, coenzymes and other metabolic intermediates
1. The Development of biochemistry and the Delineation of Glycolysis Went Hand by hand 1897, Eduard Buchner( Germany), accidental observation: sucrose(as a preservative) was rapidly fermented into alcohol by cell-free yeast extract The accepted view that fermentation is inextricably tied to living cells(i.e, the vitalistic dogma )was shaken and biochemistry was born: metabolism became chemistry 1900s, Arthur Harden and William Young Pi is needed for yeast juice to ferment glucose, a hexose diphosphate(fructose 1, 6-bisphosphate)was isolated
1. The Development of Biochemistry and the Delineation of Glycolysis Went Hand by Hand • 1897, Eduard Buchner (Germany), accidental observation : sucrose (as a preservative) was rapidly fermented into alcohol by cell-free yeast extract. • The accepted view that fermentation is inextricably tied to living cells (i.e., the vitalistic dogma) was shaken and Biochemistry was born: Metabolism became chemistry! • 1900s, Arthur Harden and William Young Pi is needed for yeast juice to ferment glucose, a hexose diphosphate (fructose 1,6-bisphosphate) was isolated
1900s, Arthur Harden and William Young(Great Britain separated the yeast juice into two fractions one heat-labile, nondialyzable zymase(enzymes) and the other heat-stable dialyzable cozymase (metal ions, ATP, ADP, NAD) 1910s-1930s, Gustav Embden and otto meyerhof (Germany), studied muscle and its extracts Reconstructed all the transformation steps from glycogen to lactic acid in vitro; revealed that many reactions of lactic acid(muscle) and alcohol(yeast) fermentations were the same Discovered that lactic acid is reconverted to carbohydrate in the presence of o2(gluconeogenesis) observed that some phosphorylated compounds are energy-rich
• 1900s, Arthur Harden and William Young (Great Britain) separated the yeast juice into two fractions: one heat-labile, nondialyzable zymase (enzymes) and the other heat-stable, dialyzable cozymase (metal ions, ATP, ADP, NAD+ ). • 1910s-1930s, Gustav Embden and Otto Meyerhof (Germany), studied muscle and its extracts: – Reconstructed all the transformation steps from glycogen to lactic acid in vitro; revealed that many reactions of lactic acid (muscle) and alcohol (yeast) fermentations were the same! – Discovered that lactic acid is reconverted to carbohydrate in the presence of O2 (gluconeogenesis); observed that some phosphorylated compounds are energy-rich
(Glycolysis was also known as Embden Meyerhof pathway The whole pathway of glycolysis(Glucose to pyruvate) was elucidated by the 1940s
• (Glycolysis was also known as EmbdenMeyerhof pathway). • The whole pathway of glycolysis (Glucose to pyruvate) was elucidated by the 1940s