Question

Why are zymogens useful in some circumstances?

Answer 1

Hint: Enzymes are protein molecules which function as biological catalysts. It helps in altering the rate of biochemical reactions occurring in the body. It can either increase or decrease the rate at which reactions occur.

Complete answer:
A zymogen is also known as a Pro-enzyme. It is an inactive form of the enzyme. And are devoid of catalytic activity. There are many methods by which a zymogen can be converted into an active enzyme. Exposure of the active site on the enzyme molecule makes it an active enzyme and is done through various processes such as hydrolysis and cleavage.

Even though zymogens have no particular function without being activated into active enzymes, it has certain advantages. One such advantage is that the secretion of inactive enzymes helps in preventing the unwanted destruction of cellular proteins. Only under favourable and required conditions zymogens are converted into active enzymes. Zymogenic cells are the cells specialized in synthesizing and storing zymogens till it gets activated.

Additional Information:
 Some examples of zymogens are as follows:
- Pepsinogen: It is the zymogen of the enzyme Pepsin. Secreted by the chief cells present in the gastric mucosa. Pepsinogen is activated into Pepsin in presence of Hydrochloric acid.
- Trypsinogen: Zymogen of active enzyme Trypsin secreted by the Pancreas. Accelerates protein digestion in the small intestine.

Note: An enzyme molecule has different parts. Apoenzyme is the globular protein part of the enzyme molecule. And it is attached to a non-protein part called co-factor or prosthetic group. Apoenzyme and cofactor together constitute Holoenzyme.