uel storage and Lipid Metabolism

Glucose storage (glycogen metabolism)
• some tissues require a continuous supply of glucose.
Initially this is met by storing glucose (as glycogen). ) glycogenesis Glycogen synthesis (

1-Glucose + ATP ? glucose 6-P + ADP catalyzed by
hexokinase (glucokinase in liver)
2. Glucose 6-P ? Glucose 1-P catalysed by
phosphoglucomutase
3. Glucose 1-P + UTP + H2O ? UDP-glucose + 2Pi
4. Glycogen (n residues) + UDP-glucose ? glycogen (n + 1
residues) + UDP
This irreversible reaction is catalyzed by two enzymes,
glycogen synthase and branching enzyme.

• If the period between meals is long to deplete the stored
glycogen (8-12 hr.) then glucose has to be synthesized
by the process of gluconeogenesis.
• Glycogen is a highly branched polymer of glucose linked
together by glycosidic bonds of two types,
?-1-4 and ?-1-6 . The ?-1-6 bonds are the branch points.

• Glycogen is a large molecule that is stored in liver and
skeletal muscle

) glycogenesis Glycogen synthesis (

1-Glucose + ATP ? glucose 6-P + ADP catalyzed by
hexokinase (glucokinase in liver)
2. Glucose 6-P ? Glucose 1-P catalysed by
phosphoglucomutase
3. Glucose 1-P + UTP + H2O ? UDP-glucose + 2Pi
4. Glycogen (n residues) + UDP-glucose ? glycogen (n + 1
residues) + UDP
This irreversible reaction is catalyzed by two enzymes,
glycogen synthase and branching enzyme.