GLYCOGEN METABOLISM. Glycogen Structure. Most of the glucose residues in glycogen are linked by a -1,4-glycosidic bonds . Branches at about every tenth residue are created by a -1,6-glycosidic bonds. Glycogen is an important fuel reserve for several reasons.
Pyridoxal Phosphate integral group of the Enzyme
The Pi substrate binding site
The T state is less active because the catalytic site is partly blocked.
The R state, catalytic site is more accessible and a binding site for orthophosphate is well organized.
The R and T states of each of the aor b forms are in equilibrium
The equilibrium for phosphorylase a, favors the R-state
The equilibrium for phosphorylase b, favors the T-state
Phosphorylase a differs from b by a phosphoryl group on each subunit
Muscular activity or its anticipation leads to the release of epinephrine (adrenaline),from the adrenal medulla.
Epinephrine markedly stimulates glycogen breakdown in muscle and, to a lesser extent, in the liver.
The liver is more responsive to glucagon, a polypeptide hormone that is secreted by the a cells of the pancreas when the blood-sugar level is low.
Net charge after posphorylation
The complete oxidation of glucose 6-phosphate yields about 31 molecules of ATP.
Storage consumes slightly more than one molecule of ATP per molecule of glucose 6-phosphate; so the overall efficiency of storage is nearly 97%.