What is the Difference Between Pepsin and Pepsinogen?

Pepsin and pepsinogen are both enzymes involved in the digestion of proteins, but they have distinct differences:

1. Activity: Pepsin is a proteolytic enzyme, while pepsinogen is a proenzyme, meaning it is the inactive precursor of pepsin.
2. Stability: Pepsinogen is stable in neutral or slightly alkaline solutions, whereas pepsin is stable in acidic solutions below pH 6. Pepsin is irreversibly denatured at pH 7 or above.
3. Digestion: Pepsin can hydrolyze proteins, breaking them down into smaller peptides and amino acids that can be easily absorbed in the intestines. Pepsinogen, being inactive, cannot perform this function.
4. Activation: Pepsin is activated by lowering the pH of the medium, whereas pepsinogen cannot be activated under the same conditions.
5. Secretion: Pepsinogen is secreted by chief cells and pyloric glands in the stomach. It is then converted to pepsin by hydrochloric acid or previously formed pepsin.

In summary, pepsinogen is the inactive precursor of pepsin, which is responsible for breaking down ingested proteins into smaller, more easily absorbed units. Pepsin has an acidic isoelectric point and requires an acidic environment for its activity, while pepsinogen is stable in both neutral and slightly alkaline conditions.

Comparative Table: Pepsin vs Pepsinogen

Here is a table comparing the differences between pepsin and pepsinogen:

Pepsin and pepsinogen are both proteases present in the stomach, playing crucial roles in the digestion of proteins. However, pepsin is the active form, while pepsinogen is the inactive precursor that is activated into pepsin by the acidic environment of the stomach.