BIOL 3361 Study Guide - Final Guide: Glycogen Phosphorylase, Phosphorylase Kinase, Adenylyl Cyclase
Document Summary
Lecture 21: glycogen metabolism and pentose phosphate pathway. Synthesis and degradation of storage glycogen: tightly regulated. Both catabolic and anabolic enzymes are present in glycogen granules. Glycogen phosphorylase: cleaves one sugar unit from the end of a glycogen chain; uses inorganic phosphate to phosphorylate the glucose. (avoids using atp for phosphorylating glucose) This is called phosphorolysis: (instead of hydrolysis) glycosidic bond is split by p instead of water. Muscles: g-6-p enters glycolysis transport to other tissues. First transfers a disaccharide unit from one branch to the end of another a1,6 glucosidase: Hydrolyzes at the branch point using a1,6 glucosidase activity (glucose) A-amylase (in saliva and pancreatic secretions) is an endoglycosidase: hydrolyzes the a1,4 linkages of glycogen, products: maltose (disaccharide), maltotriose (trisaccharide), small oligosaccharides, also leaves highly branched limit dextrin (degraded by debranching enzyme) White subunit: with helices and loops important for regulation shown in blue & red. Yellow subunit: with regulatory structures shown in orange and green.
