glycogenolysis Flashcards
What kind of bonds make up glycogen
striaght links-α1,4 glycosidic bonds
Branch points formed via α-1,6 glycosidic
_____ ________ends each contain a terminal glucose
with a free hydroxyl group at Carbon 4
_______ end consists of glucose monomer connected
to a protein called glycogenin
Non-reducing ends each contain a terminal glucose
with a free hydroxyl group at Carbon 4
• Reducing end consists of glucose monomer connected
to a protein called glycogenin
where is glycogen degraded and extended from
Glycogen is degraded and extended from nonreducing end.
where is glycogen stored and how is it stored
stored in the liver and muscle in granules
what is the function of liver glycogen? muscle glycogen
Liver glycogen - regulates blood glucose
levels
• Muscle glycogen - provides reservoir of
fuel (glucose) for physical activity
What are the 3 ways glycogen metabolism is regulted
Allosteric control
Covalent modification through reversible
phosphorylation of key enzymes
Hormonal control
What are the 3 key steps of glycogenesis
trapping and activated glucose
elongation of glycogen primer
branching of glycogen chains
What are the main steps of trapping glucose inside cell
glucokinase converts glucose–> G-6-P
phophoglucomutase isomerizes G-6-P –> G-1-P
Uridine diphosphate(UDP)-glucose pyrophosphorylase then transfers the glucose-1-
phosphate to uridine triphosphate (UTP) which
generates UDP-glucose (active form of glucose)
—> UPi + G-1-P=UDP
what is the rate limiting enzyme of glycogenolysis
glycogen synthase- catalyzes the transfer of UDP glucose tp non reducing end
How long does glycogen chain reach before first branch point is created
11 residues
what enzymes catalyzes the formation of glycogen branch point
α-1, 6 link by glucosyl (4:6) transferase.
What are the main steps of glycogenolysis
G-1–P –> G-6-P–> glucose
What are the 4 key enzymes of glycolysis and what are their roles
glycogen phosphorylase: degrade glycogen ( chain shortening)- cuts by adding ortho phosphate within 4 residues of the branch point
two remodeling enzymes
–>phosphoglucomutase Converts Gluc-1-phosphate to Gluc-6-phosphate
–> Debranching enzyme or α-1,6 glucosidase cleaves the α1,6 bond of the single remaining glucose residue to release the
free glucose.
glucose-6-phosphatase- converts G-6-P to glucose-convert product into something suitable for metabolism ( not present in muscle cells so G-6-P is trapped
Pompe disease is cause by dysfunction of what enzyme?
lysosomal alpha-1,6-glucosidase
