Chapter 24: Glycogen Degradation

glycogen phosphorylase

the key regulatory enzyme in glycogen breakdown. cleaves its substrate by the addition of orthophosphate (Pi) to leave glucose 1-phosphate

1,6

The α-___-glycosidic bonds at the branch points are not susceptible to cleavage by phosphorylase

Transferase

shifts a block of three glucosyl residues from one outer branch to another

alpha-1,6-glucosidase

also known as the debranching enzyme, then hydrolyzes the bond,

resulting in the release of a free glucose molecule

phosphorolysis

The cleavage of a bond by the addition of orthophosphate is referred to as

Phosphoglucomutase

converts glucose 1-phosphate into glucose 6-phosphate

phosphorylated serine

Active site of phosphoglucomutase contains a _____________ residue

C-6 hydroxyl, glucose 1,6-bisphosphate

The phosphoryl group is transferred from serine residue to _________ group of G1P to form ________________

C-1 phosphoryl, serine, glucose 6-phosphate

The ________ group of this intermediate is then shuttled to the same ______ residue, resulting in the formation of ___________ and the regeneration of the phosphoenzyme

liver

which part of body contains glucose 6-phosphatase

glucose 6-phosphatase

enzyme that cleaves glucose 6-phosphate into glucose

Phosphorylase

______________ is a key regulatory enzyme and exists in two forms: a and b

a form

_____ is the more active form (R state); phosphorylated phosphorylase

b form

_____ is the less active form (T state); unphosphorylated phosphorylase

-

draw out phosphoglucomutase mechanism

-

draw out epinephrine pathway mechanism

Protein phosphatase 1 (PP1)

removes phosphoryl groups from phosphorylase kinase and glycogen phosphorylase