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10-2 Glycogen (starch) metabolism

10-2 Glycogen (starch) metabolism. Figures : Stryer-5ed; chapter: 21 Lehninger-4ed; chapters: 7, 15, 23. The structure of starch. Branch points occur every 24 to 30 residues!. amylopectin. The structure of amylose. The structure of glycogen.

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10-2 Glycogen (starch) metabolism

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  1. 10-2 Glycogen (starch) metabolism Figures: Stryer-5ed; chapter: 21 Lehninger-4ed; chapters: 7, 15, 23

  2. The structure of starch Branch points occur every 24 to 30 residues! amylopectin

  3. The structure of amylose

  4. The structure of glycogen More branched and compact: branch points occur every 8 to 12 residues!

  5. Glycogen (starch) degradation (glycogenolysis)

  6. Pyridoxal phosphate cofactor (also in amino acid metabolism)

  7. Glycogen synthesis (glycogenesis) D-Glucose + ATP  D-glucose-6-phosphate + ADP (hexokinase) Glucose-6-phosphate  glucose-1-phosphate (phosphoglucomutase) Glucose-1-phosphate + UTP  UDP-glucose + PPi(UDP-Glc pyrophosphorylase)

  8. UDP-glucose is the substrate for glycogen synthesis ADP-glucose is the substrate for starch synthesis in plants

  9. The cost of converting Glc-6-P into glycogen: Glucose-6-phosphate  glucose-1-phosphate (phosphoglucomutase) Glucose-1-phosphate + UTP  UDP-glucose + PPi (UDP-glucose phosphorylase) PPi + H2O  2Pi (inorganic pyrophosphatase) UDP-glucose + glycogen (n)  glycogen (n+1) + UDP (glycogen synthase) UDP + ATP  UTP + ADP (nucleoside diphosphate kinase) Sum: Glc-6-P + ATP + glycogen (n) + H2O  glycogen (n+1) + ADP + 2Pi

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