Glycogen Metabolism Flashcards
(23 cards)
What are the main stores of glycogen?
Liver and skeletal muscle
Structure of glycogen
Branched chain polysaccharides Made from alpha glucose
The primary glycosidic bind in an alpha 1,4 linkages
After every 8 -10 gkycosidic residue, there is a branch containing and alpha I,6
A glycogen molecule can have a weight of
108 daltons
Synthesis of glycogen
Synthesized from D glucose in the cytosol and uses energy in the form of ATP and UTP
Synthesis of UTP
Alpha D glucose attached to uridine phosphate is the source of the glucosyl residues that are added to the growing glycogen molecule.
UDP glucose is synthesized from glucose 1- phosphate and glucose by the enzyme?
UDP glucose pyrophosphorylase
Glucose 1- phosphate is synthesis from glucose 6 phosphate by
Phosphoglucomutase
The high energy bond in PPi is hydrolyzed by
pyrophosphatase
Inter conversion of glucose 6 phosphate and glucose 1 phosphate is done by
Phosphoglucomutase
Which enzyme makes the alpha 1-4 bonds in glycogen?
Glycogen synthase
This enzyme can acts as an acceptor of glucose residues from UDP glucose
Glycoenin
Elongation of glycogen chains
Elongation of a glycogen chain involves the transfer of glucose from UDP- glucose to the non reducing end of the growing chain forming a new gkycosidic bond between the anomeric hydroxyl Of carbon 1 of the activated glucose and carbon 4 of the accepting glycogen residue.
What increases the rate of gkycogen synthesis?
The branching of the glycogen, gives it more souble and increases the number of non reducing end where new glucosyl residues can be added .
Which enzymes makes branches?
Amylo- alpha (1,4), alpha (1,6) transglucosidase
In degradation , glycogen is degraded to glucose 1 phosphate by th breaking of
Alpha 1,4 bonds
The cleaving of the alpha (1,4) glycosidic bonds between the glucosyl residues at the on reducing ends of the glycogen chain producing glucose 1 phosphate is done by?
Glycogen phosphorylase
Four glucosyl units on each chain that can be degraded any longer is called
A limit dextrin
The removal of branches by a two enzymatic of a single bifunctional protein is done by
The debranching enzyme
The outer three of the four glucosyl residues attached at a branch is done by
Oligo (1,4) glycan transferase activity
The remaining single chain is attached to the (1,6) linkage is removed hydroltically by
Amylo alpha (1,6) glucosidase activity
Which enzyme transports glucose 6 phosphate into the ER
Glucose 6 phosphate translocase
The regulated enzyme in glucogenesis is
Glycogen synthase
Protein phosphatase 1 Is stimulated by
Insulin
