BIOCHEMISTRY - L. Stryer - 1984

VOLUME 2

PART II GENERATION AND STORAGE OF METABOLIC ENERGY

CHAPTER 16. GLYCOGEN AND DISACCHARIDE METABOLISM

QUESTIONS AND PROBLEMS

1. Write the equilibrium equation for The formation of Glycogen from galactose.

2. Write the equilibrium equation for the formation of glucose from fructose in the Liver.

3. A glycogen sample from a patient with a liver disorder is incubated with orthophosphate, phosphorylase, transferase, and the debranching enzyme. The ratio of glucose-1-phosphate to glucose produced in this mixture is 100. Which enzyme deficiency is most likely in this patient?

4. How can you account for the fact that The amount of glycogen is increased in type I glycogen storage disease (Von Gierke disease)?

5. Crystals of phosphorylase a growing in the presence of glucose are disrupted upon The addition of a substrate such as glucose-1-phosphate. Why?

6. Muscle phosphorylase kinase is a very large enzyme (1300 kDa) with an A₄B₄C₈ subunit Structure. Phosphorylation of the B subunits of this enzyme by cyclic AMP-dependent kinase occurs rapidly and leads to its activation. The A subunits of the enzyme are subsequently phosphorylated at a slow rate; consequently, both the A and B subunits become susceptible to the action of a specific phosphatase. What is the probable Functional Significance of the slow phosphorylation of the A subunits?