BIOCHEM 2EE3 Lecture Notes - Lecture 9: Glycogen Phosphorylase, Glycogen Synthase, Citric Acid Cycle
14 Mar 2016
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Document Summary
Glycolysis: 10-step pathway occurs in cytosol; both anabolic and catabolic process (provides biosynthetic intermediates for amino acids); strongly exergonic. Rst 5 steps= energy investment phase: at the expense of 2 atp, sugar is activated by phosphorylating (priming) yielding fructose-1,6-bisphosphate cleavage yields two 3-c sugar phosphates (triose phosphates) Glycogen: stored primarily in the liver and muscle; highly branched structure; single reducing end (glucose residues removed for rapid mobilization) and several nonreducing ends; -1,4 bonds form linear linkages, -1,6 bonds form the branch points. Glycogen phosphorylase catalyzes the phosphorylation of glycogen, releasing glucose-1-phosphate which is converted to glucose-6-phosphate by phosphoglucomutase which then can enter glycolysis. Glycogen synthase catalyzes the synthesis of glycogen using utp. Glycogen phosphorylase and synthase are controlled by allosteric regulation and covalent regulation by phosphorylation ensures these processes are not futile; match the supply of atp for the demand for energy based on metabolic needs.
