10. Glycogen metabolism- Glycogenesis and Glycogenolysis скачать в хорошем качестве

10. Glycogen metabolism- Glycogenesis and Glycogenolysis

Glycogen metabolism Glycogen Homopolysaccharide of glucose with alpha 1-4 glycosidic linkage in linear chain and alpha 1-6 at branching point Branching make molecule more globular, compact and less space consuming Metabolism includes 1. Glycogenesis 2. Glycogenolysis Glycogenesis Synthesis of glycogen from glucose Key enzyme- glycogen synthase Steps 1. Activation of glucose to UDP-glucose 2. Addition of glucose to primer/ glycogenin 3. Elongation up to 10 to 12 glucose units 4. Branching by forming alpha 1-6 linkage by branching enzyme 5. Elongation 6. Branching 7. Glycogen Glycogenolysis Synthesis of glucose from glycogen Key enzyme- glycogen phosphorylase Steps 1. Removal of glucose in the form of glucose 1 phosphate 2. Limit dextrin formation 3. Transfer of trisaccharide unit from branching point to linear chain by transferase 4. Breaking of alpha 1-6 linkage and liberation of Free glucose by debranching enzyme 5. Again removal of glucose in the form of glucose 1 phosphate 6. Conversion of glucose 1 phosphate to glucose 6 phosphate 7. Glucose formation REGULATION glycogen synthase active in dephosphorylated state And Glycogen phosphorylase active in phosphorylated state Insulin favours the glycogenesis by decreasing cAMP and glucagon favours glycogenolysis by increasing cAMP Glycogenesis is inhibited by Glucagon in Liver