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.
P phosphorylase are approximately 90% identical in amino acid sequence.
Depending on phosphorylase are approximately 90% identical in amino acid sequence.
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.Epinephrine and Glucagon Signal the Need for Glycogen Breakdown
Net charge after posphorylation of glycogen.Glycogen Synthase Is the Key Regulatory Enzyme in Glycogen Synthesis
Glycogen of glycogen.
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%.