Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 11

Biological Relevance. Explain the biological relevance of each of the following observations concerning enzyme regulation.
(a)When you need a burst of energy, the hormones epinephrine and glucagon are secreted into your bloodstream and circulated to your muscle cells, where they initiate a cascade of reactions that leads to the phosphorylation of the inactive b form of glycogen phosphorylase, thereby converting the enzyme into the active a form.
(b)Even in the a form, glycogen phosphorylase is allosterically inhibited by a high concentration of glucose or ATP within a specific liver cell.
(c)Your pancreas synthesizes and secretes the proteolytic enzyme carboxypeptidase in the form of an inactive precursor called procarboxypeptidase, which is activated as a result of proteolytic cleavage by the enzyme trypsin in the duodenum of your small intestine.