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.
Phosphorylation produces an alteration of charges on the protein and causes its inactivation: it converts the active form a of synthase into a completely inactive form b.
b. Even in the a form, glycogen phosphorylase is allosterically inhibited by a high concentration of glucose or ATP within a specific liver cell.
Although the nature of the metabolites involved in regulating enzymes is very varied, it is very common to find adenylates (ATP, ADP and AMP) as allosteric effectors. The use of these compounds as effectors makes it possible to coordinate the rate of ATP formation with that of its use. A. Any small change in ATP or ADP concentrations will result in relatively large changes in [AMP]. Thus, enzymes that have AMP as an allosteric effector are sensitive to small changes in [ATP] or [ADP].
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.
The pancreas is a mixed gland of both endocrine and exocrine character. Its main content is the enzymes that degrade practically all the nutritional principles and that are synthesized and stored in the acinar cells. So there are: Procarboxypeptidase whose activator is trypsin breaks carboxylic bonds of terminal amino acids that have aromatic or branched side chains.
Explanation:
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.
Phosphorylation converts the inactive form (b) into the active form (a). There are two forms of the enzyme that break down glycogen, glycogen phosphorylase a (phosphorylated and active) and phosphorylase b (dephosphorylated and inactive). Phosphorylation at a serine residue of each phosphorylase b subunit causes it to be converted to phosphorylase a, and that phosphorylation is catalyzed by phosphorylase b kinase. The phosphorylated form b requires a high level of the allosteric activator glucose 6-phosphate to activate, whereas form a is active whether or not glucose 6-phosphate is present. Phosphorylase b kinase is activated in turn, by phosphorylation and also by high level of Ca2 + in muscle. The enzyme that catalyzes this last phosphorylation, of phosphorylase b kinase, is protein kinase, which in turn is activated by the binding of cAMP, interacts differently with the phosphorylated and dephosphorylated form of the enzyme, thus resulting in an extremely regulatory process. sensitive. In this way, high levels of AMP activate form b of the enzyme and ATP and G-6-P inhibit it.
b. Even in the a form, glycogen phosphorylase is allosterically inhibited by a high concentration of glucose or ATP within a specific liver cell.
The regulation of glycogen degradation is exerted at the level of glycogen phosphorylase. GP is regulated by two mechanisms: Allosteric regulation by metabolites: AMP in muscle and glucose in liver. AMP is a positive allosteric effector or activator of muscle phosphorylase, it binds to phosphorylase b and activates it, thus acting when the energy state of the muscle is low. ATP can reverse this activating effect. The high concentration of glucose in the blood switches off or deactivates the degradation of glycogen in the liver.
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.
The exocrine portion has an acinar structure, and its secretion is absolutely essential for digestive processes. The exopeptidases of pancreatic juice are carboxypeptidase A and B. The first hydrolyzes peptide bonds at the carboxyterminal end, releasing any type of amino acid except arginine, lysine and proline. Carboxypeptidase B also hydrolyzes carboxy-terminal peptide bonds, but only when the carboxy-terminal amino acid is arginine or lysine. Procarboxypeptidase A is one of the zymogens that make up the pancreatic secretion that is discharged into the duodenum. In the intestine it produces its activation limited proteolysis that gives rise to the appearance of carboxypeptidase A in active form.
