BIBC 102: Metabolic Biochemistry (Prof. Scheffler) TA: Edward Chen [email protected] Section: Mondays 4-5pm Center 218 OH: Wednesdays 10-11am @ CLICS Images taken from Principles of Biochemistry, 4th edition,by Lehninger et al, 2005 Handout #3 (2/6/06) A. UDP-glucose • Structure: • How to get from UDP-galactose to UDP-glucose: B. Pathways • Catabolic o Glycogenolysis: o Glycolysis: • Anabolic o Gluconeogenesis: o Glycogenesis: C. Glycogenolysis: • 3 major enzymes: o glycogen phosphorylase o glycogen debranching enzyme o Phosphoglucomutase • Reducing end and non-reducing end See slide 7-21, bottom half D. Glycogen phosphorylase • Sequential removal of non-reducing end of glucose from glycogen and turns them into glucose 1-phosphate. • (Glu)BnB + Pi → (Glu)Bn-1B + Glu 1-P • cofactor: E. Glycogen debranching enzyme • Basically, debranches glycogen • 2 steps: o Transferase activity At, (2, 4), cuts off branch and adds it to the end to form (1,7) o Glucosidase activity Breaks off last branched glucose and frees it, leaving a linear polymerBIBC 102: Metabolic Biochemistry (Prof. Scheffler) TA: Edward Chen [email protected] Section: Mondays 4-5pm Center 218 OH: Wednesdays 10-11am @ CLICS Images taken from Principles of Biochemistry, 4th edition,by Lehninger et al, 2005 F. Phosphoglucomutase • Glu-1-P ↔ Glu-6-P • See page 564 G. Glycogen Synthesis • Glycogenin: o UDP allows the polymerization to occur • Glycogen synthase: • Branching enzyme: o Each branch has about 12-14 glucose residues • See slide 7-39, 7-40, 7-41 H. Control of Glycogen Synthesis and Breakdown • SLIDE 7-49!, LNC 15-24, U15-25, 15-26U (!!!!!)^2 Covalent modificationsBIBC 102: Metabolic Biochemistry (Prof. Scheffler) TA: Edward Chen [email protected] Section: Mondays 4-5pm Center 218 OH: Wednesdays 10-11am @ CLICS Images taken from Principles of Biochemistry, 4th edition,by Lehninger et al, 2005 Example Problems (From Prof. Scheffler’s old exams): 1. Explain why the phosphorolysis of glycogen is more efficient than the hydrolysis of glycogen in mobilizing glucose for the glycolytic pathway. 2. Explain with a highly schematic diagram how a branched molecule of glycogen can be degraded more rapidly than an unbranched molecule with the same number of monomers 3. Diagram the pathway from glucose to glycogen; show the participation of all substrates and give a generic name of the enzymes involved. 4. We have seen how critical enzymes in a pathway can be regulated by a variety of mechanisms. Use the Uglycogen phosphorylaseU as an example to describe two UdistinctU mechanisms for modulating the activity of an enzyme. A description and schematic diagrams should be used 5. A somewhat inexperienced researcher wants to make radioactive glucose-6-phosphate from glucose and ATP. He looks in a catalogue and orders α[P32PP]-ATP from a biochemical supply company. What enzyme would he need? When he tries the reaction with the required enzyme, he is disappointed by the failure to get radioactive phosphorylated sugar. Can you explain
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