The glycogen formation in is performed by three enzymes:

Maltose occurs to a limited extent in sprouting grain. It is formed most often by the partial hydrolysis of starch and glycogen. In the manufacture of beer, maltose is liberated by the action of malt (germinating barley) on starch; for this reason, it is often referred to as . Maltose is about 30% as sweet as sucrose. The human body is unable to metabolize maltose or any other disaccharide directly from the diet because the molecules are too large to pass through the cell membranes of the intestinal wall. Therefore, an ingested disaccharide must first be broken down by hydrolysis into its two constituent monosaccharide units. In the body, such hydrolysis reactions are catalyzed by enzymes such as . The same reactions can be carried out in the laboratory with dilute acid as a catalyst, although in that case the rate is much slower, and high temperatures are required. Whether it occurs in the body or a glass beaker, the hydrolysis of maltose produces two molecules of D-glucose.

All glycogen synthesis genes were successfully cloned into BioBricks.

Which of the following statements about glycogen and its catabolism is NOT true?

Muscle can't mobilize fat as quickly as it can glycogen.

Active cAMP-dependent protein kinase phosphorylates glycogen phosphorylase kinase (phosphorylase kinase), converting it from the inactive "b" for to the active "a" form. Active cAMP-dependent protein kinase phosphorylates the inhibitor 1 protein, activating it to bind to and inhibit protein phosphatase 1, and also phosphorylates protein phosphatase 1 directly, causing its inhibition. As a result the activating phosphate on phosphorylase kinase is not removed by protein phosphatase 1 and phosphorylase kinase remains active as long a glucagon or epinephrine signaling continues.

Glycogen branching enzyme

This invention relates to glycogen biosynthesis enzymes in plants. In particular, this invention is directed to plant cells having a DNA sequence encoding a glycogen biosynthesis enzyme integrated in its genome as the result of genetic engineering. Cells containing a DNA or RNA (mRNA) sequence encoding the enzyme as well as cells containing the enzyme are also provided. Plants and, more particularly, plant parts may also be obtained which contain glycogen biosynthesis enzyme sequences and/or containing such glycogen biosynthesis enzymes.

When glycogen is synthesized in both the liver and muscle, all of the following are true EXCEPT

Glycogen (or Maltodextrin) + Pi

Calcium/calmodulin associates as a subunit with several enzymes and modifies their activities. It binds to inactive phosphorylase kinase, partially activating it — the fully active enzyme is both bound to the calcium/calmodulin and phosphorylated. Phosphorylase kinase phosphorylates glycogen phosphorylase b, thereby activating glycogen degradation. Calcium/calmodulin is an activator of one of the glycogen synthase kinases (calcium/calmodulin synthase kinase). Protein kinase C, calcium/calmodulin synthase kinase, and phosphorylase kinase all phosphorylate glycogen synthase, inhibiting it, and therefore, glycogen synthesis.

Glycogen (or Maltodextrin) + α-glc-1-P


In the next step, and were fused in pSB1C3 via Gibson Assembly and CPEC. We decided to put at the first position within the reading frame. The amount of ADP-glucose created by GlgC determines the activity of the following two enzymes and can therefore be considered the bottleneck of glycogen synthesis. We obtained with a point mutation in the sequence of , changing one alanine to a similiarly aliphatic aminoacid, valine. We tried to correct the substition via QuikChange and new Gibson Assembly/CPEC. Despite multiple attempts, we always received the same point mutation again. When we analysed the tertiary structure of GlgB, we assessed that the mutation was not positioned in the active site and should therefore not impede its function a lot. Due to time reasons we decided to proceed with the mutated construct which was subsequently cloned into pSB1A30 in order to confirm gene expression by .

When glycogen is degraded (catabolized), all of the following occur in both liver and muscle EXCEPT

Glycogen Branching

Epinephrine in the liver enhances or is synergistic with the effects of glucagon. Epinephrine release during hypoglycemia or exercise can stimulate hepatic glycogenolysis and inhibit glycogen synthesis very rapidly.

The liver can store excess glucose as glycogen.

11. Answer: D. Chapter 28, Objective 11: What is the effect of changes in the insulin, blood glucose or epinephrine upon glycogen synthesis or glycogen degradation in muscle?

Enzymatic preparation of the glycogen-mimic substrate.

12. Answer: E. Chapter 28, Objective 12: In order of their activation, be able to name and give the reason for the activation of all the intermediates in the cAMP cascade in liver. Start with a decrease in the insulin/glucagon ratio or an increase in epinephrine and end with the change in activity of glycogen synthase, phosphorylase kinase and phosphorylase a?