Glycogenolysis Enzymes
This enzyme is responsible for breaking a(1->4) glycosidic bonds until a limit dextrin is left.
What is glycogen phosphorylase?
Your patient presents with high levels of glycogen and complaints of pain in their muscles after exercising; after taking a blood lactate level during exercise, lab results come back normal. Patient is likely afflicted with this disease.
What is Type V: McArdle Syndrome (Skeletal Muscle Glycogen Phosphorylase Deficiency)
These hormones are responsible for activating glycogenolysis in muscle and liver cells.
What are glucagon and epinephrine?
What is insulin?
This is where glycogen is primarily stored and readily available when exercising.
What are muscles?
This enzyme is responsible for cleaving the remaining a(1->4) glycosidic bonds in the limit dextrin.
What is 4:4 transferase?
What is Type II: Pompe Disease?
This enzyme, when activated by a chain reaction initiated by glucagon/epinephrine binding to GPCRs, is responsible for phosphorylating glycogen phosphorylase and turning on glycogenolysis
What is phosphorylase kinase?
A rise in blood glucose will cause this hormone to be released.
What is insulin?
Glycogen is released from this organ when blood sugar is low.
What is the liver?
This enzyme cleaves the a(1->6) bond in the last glucose of the limit dextrin.
What is 1:6 glucosidase?
Patient experiences hypoglycemia when fasting. Upon analysis of glycogen, structures appear abnormal, with 1 or 4 glucosyl residues at branch points.
What is Type III: Cori Disease?
The presence of this high energy molecule in large concentrations will inhibit glycogenolysis.
What is ATP?
When the body is under physiologic stress (intense exercise, fight or flight response, etc.), insulin secretion will be inhibited by these two neurotransmitters.
What are epinephrine and norepinephrine?
This end of glycogen is where more glucose monomers are added.
What is the non-reducing end?
This enzyme converts free glucose 1-phosphate to glucose 6-phosphate.
What is phosphoglucomutase?
What is Type 1a: Von Gierke Disease?
This process is favored when energy and glucose are low.
What is glycogenolysis?
This hormone is secreted in response to hypoglycemia, high amino acids (for GNG), and high catecholamines.
What is glucagon?
This is the tyrosine-containing protein that binds with UDP-glucose to form the glycogen primer.
What is glycogenin?
These are the two primary products of glycogenolysis.
What are glucose 1-phosphate and free glucose (from branch points)?
Putting it all together: we can assume that all patients previously mentioned will have low blood glucose levels because .... (not in Jeopardy format)
The body is not able to properly metabolize glycogen to release glucose into the blood.
The presence of this low-energy adenosine derivative in high concentrations can turn on glycogen phosphorylase.
What is AMP?
(Remember: high concentrations of cAMP are produced by adenelyl cyclase when glucagon or epinephrine bind to GPCRs --> glycogen metabolism)
This hormone inhibits fatty acid synthesis.
What is glucagon?
This is the amount of energy stored in a diphosphate molecule, the same amount released when hydrolyzed.
What is -33.5 kJ/mol?
What's important here is not so much the amount of energy, but the fact that it has a negative deltaG. This means it is exergonic, and this is why, when coupled with UDP-glucose formation (no change in Gibbs free energy), the reaction is driven forward.