Biochem - Glycogen Flashcards
Draw out glycogenesis pathway
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Draw out glycogenolysis pathway
Page 539
McArdle disease – Type V
Glycogen phosphorylase deficient
Muscle cells accumulate glycogen
-> water influx -> lyse
cause Rhabdomyolysis -> myoglobulinuria, renal failure
muscle cramping
normal life expectancy
Von Gierke disease (type I)
Glucose 6 phophatase deficiency
-liver, enterocytes, kidney
severe fasting hypoglycemia
glycogen buildup in liver -> hepatomegaly
enlarged kidneys
elevated serum lactate
elevated uric acid
Hypertriglyceridemia
Tx: frequent meals, cornstarch at night
Cori disease (typeIII)
Alpha-1,6-glucosidase deficiency
Can’t break down 1,6; but can break down 1,4 linkages
Milder hypoglycemia
No elevation of lactate level
No elevation of uric acid
Pompe disease – deficiency
Deficiency of alpha-1,4-glycosidase in lysosomes
Pompe disease infantile form
No enzyme activity
Severe muscle weakness
Cardiomegaly and heart failure
Shortened life expectance less than 1 yr untx
Pompe disease adult form
Some enzyme activity No cardiac involvement Gradual onset of sk.m. weakness Diaphragm weakness Respiratory failure
Alpha 1,6 glucosidase activity
Part of glycogenolysis pathway
Transferase activity:
4 alpha d-gluconotransferase
-3 of last 4 glucose molecules left by glycogen phosphorylase transferred to another chain
Alpha 1,6 glucosidase activity removes last glucose molecule of branch.
Glycogen regulation
Insulin: inhibits glycogen phophorylase – stimulate glycogen synthesis
High stress tate: epi and glucagon release – counter regulatory hormones
Glucagon: stimulates adenylyl cyclase -> cAMP -> PKA ->
Glycogen phophorylase kinase -> glycogen phosphorylase -> glycogenolysis
Epinephrine:
b-adrenergic receptors stimulates adenylyl cyclase -> glycogen phosphorylase -> glycogenolysis
