Question

Explain how camels can manage without water in desert? Explain the molecular mechanism. (1 point)

Answer 1

Pepsin and trypsin

Zymogen is an inactive form of an enzyme which requires activation or a conformational change to form the active enzyme.

Tha activation can be by chemical change such as change in ionic concentration or pH change or by a cofactor or a coenzyme which changes the protein conformation of the enzyme and exposes the active site of the enzyme for binding.

Pepsinogen is such a zymogen which is secreted in the gastric juices in the digestive system. Pepsinogen is a precursor of pepsin enzyme which breaks down the peptides in protein molecules into amino acids. Therefore it is necessary for pepsinogen to be inactive until it reaches its target location, else it will digest the protein molecules in the cells which synthesize it. Pepsinogen is secreted by the cells of the epithelial lining of the stomach. Once pepsinogen is secreted in the stomach, it comes in contact with the hydochloric acid in the stomach. As a result of the low pH, the unfolding and activation of pepsinogen into pepsin is facilitated.

Trypsinogen is a zymogen which is secreted in the pancreatic juice produced by pancreas. Trypsinogen is a zymogen of trypsin enzyme which breaks down the proteins in the food molecules and facilitates the digestion process. Trypsinogen is produced in the acinar cells of the pancreas; and therefore it is necessary for it to be inactive or else it will act on the proteins of these pancreatic cells itself. Once trypsinogen is released into the small intestine, it is activated by another enzyme enterokinase sectered by the cells of duodenum (first part of the small intestine). Enterokinase activates trypsinogen by peptide cleavage which results in some conformational change in the trypsinogen molecule resulting in the formation of active trypsin enzyme.