Question

24. How does insulin end up with 2 separate chains when it is produced as one sequence o amino acids. (4 points) 25.What is the difference between the hydrogen bonding which holds the secondary protein structures of and alpha helix and a beta pleated sheet together and the hydrogen bonding that holds the tertiary structure together? (4 points) 26. List the 6 classes of enzymes and describe what types of reactions they catalyze. (3 points per class of enzymes, 18 points total) 0 0xidored uctases catalyze oxidatun q reluctem reachins ascs Catalypes additim or rem deuble bond

Answer 1

24. In the endoplasmic reticulum of beta cells the proinsulin molecule is cleaved giving the A and B chains of insulin and an inactive C peptide. The A and B chains become linked together via two sulfur-sulfur (disulfide) bonds. Further during reavreac if these Sulfur sulfur bonds break, the two chains become separate.

25. The secondary structure are held together by classical hydrogen bonds where in bond between Hydrogen bonded to nitrogen and oxygen of the groups of the same chain occur. Here the hydrogen bonds are always between NH and CO.

Hydrogenbond in tertiary structure - in case of tertiary structure, hydrogen bonds take place between the side groups and not on the backbone of the same chain. Since in tertiary structure the chains are coiled and compressed closely these kind of interaction are possible.

Many of the groups on the side chain have hydrogen atoms attached to an oxygen atom or nitrogen atom. Here hydrogen bonding can occurs. Here hydrogen bonds may be between NH and CO or between OH and CO etc.