Question

What are zymogens? How is chymotrypsinogen different from chymotrypsin?

Hint:

Understand the process of zymogen activation, and note the structural differences that cause them to be inactive and active.

Answer 1

Zymogens: Zymogens, also called proenzymes, are inactive precursors of proteolytic enzymes. They are stored in this inactive state so that they don’t cause unwanted damage to cells. Chymotrypsinogen vs. Chymotrypsin: Chymotrypsinogen: This is the inactive precursor of chymotrypsin. It does not possess enzymatic activity on its own. Chymotrypsin: This is the active enzyme, formed after modification of chymotrypsinogen through proteolysis. Active Site: In the chymotrypsinogen, the substrate-binding pocket is blocked, and it is not exposed. However, once it is transformed into chymotrypsin, this pocket is made exposed. Serine: In chymotrypsinogen, the Serine 195 in the active site is not acidic, but once it has been transformed to chymotrypsin, the Serine 195 becomes acidic. Charge Relay: Charge relay system in chymotrypsinogen does not function, whereas in chymotrypsin, it starts to operate, making it active.