Glycogen metabolism=Synthesis
Terms
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- What is most important junction point?
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Glucose-6-phosphate
G-6-Pi is in equilibrium with Glucose-1-pi
G-6-pi means use it
G-1-pi means store it - Phosphoglucomutase
- changes Glucose-6-pi into Glucose-1-pi which can be stored as Glycogen
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Bond configuration in Glycogen
1=Branch point
2=Unbranched chain -
1= alpha 1-6-glycosidic bond
2= alpha 1-4 glycosidic bond - Reducing vs. non-reducing end
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Anomeric C at reducing end
Glucose liberated from non reducing end. - Structure of Glycogen
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Glycogenin core
primer
2nd, 3rd, and 4th tier (12 tot.)
2k non reducing ends, 55k glucoses - Phosphoglucomutase mechanism
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adds a pi to G-1-pi to getG-1,6-BP
Le chatlier principle, conc. of each decides which way rxn. goes to G-1-pi or G-6-pi - UDP glucose pyrophosphorylase
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Activates glucose molecule-
Glucose 1-6 phosphate is attached to UTP(uridine triphosphate) by UDP glucose pyrophosphorylase. A PPi released and that drives rx. forward. Product is UDP glucose which is ready for addition - Action of building Glycogen
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Glycogenin core initiates rxn.
adds glucose from UDP glucose to a tyrosine residue of itself. Glycogenis catalyzes addition of firts 8 glucoses
Glycogen Synthase then adds rest of glucose - Glycogen branching enzyme
- after addition of aboiut 11 glucoses is removes 7 and makes a alpha 1,6 branch
- Glycogen Synthase
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enzyme that adds glucoses to glycogen from udp-glucose
active=no pi
inactive=pi