Glycogen Flashcards
Glycogen structure and nature?
Spherical molecule attached to primer protein. Doesn’t pull as much water as free glucose
Which end of the glycogen would react with Fehlings solution?
Reducing end. But it is attached to glycogenin
What do glycosidic bonds do?
Prevent glucose rings from opening
Where does branch point attach on carbon?
6’ carbon
How does glycogenin limit glycogen size?
Glycogen synthase must be attached to glycogenin, limiting range
Structure of glycogen vs starch?
Identical, with glycogen having far more branches. 8-12 residues vs 24-30
What does phosphoglucomutase do?
It changes G6P to G1P
How is UDP glucose made?
ATP to UTP, reacts with glucose to make UDP glucose.
What happens to UDP glucose?
Added to glycogen, releasing UDP. Linear alpha 1,4 bond
How does branching occur in glycogen?
Never at chain end. Branching enzyme finds monomer, breaks off branch and attaches it there. No energy used
What does glycogen phosphorylase do and produce?
Breaks down glycogen to G1P and shorter glycogen.
How are glycogen branches removed?
By debranching enzyme. 2 parts, transferase moves branch leaving one glucose behind, which is removed by glucosidase.
Where does epinephrne act on glycogen? Glucagon?
Muscle
Liver
How are glycogen synthase and phosphorylase regulated?
Reciprocally. Protein kinase A inhibits new glycogen, promotes breakdown. Phosphatase does reverse
What can overcome protein kinase a regulation of glycogen? Phosphatase ?
G6P
Ca++
