Let me share with you a comparison between pepsin and pepsinogen.
| Aspect | Pepsin | Pepsinogen |
| Introduction | Enzyme that breaks down proteins in the stomach | Inactive precursor of pepsin, secreted by gastric chief cells |
| Form | Active enzyme | Inactive proenzyme |
| Activation | Derived from pepsinogen through exposure to acidic environment in the stomach | Secreted in an inactive form and activated by hydrochloric acid (HCl) in the stomach |
| Function | Catalyzes the hydrolysis of peptide bonds in proteins, breaking them down into smaller peptides | Serves as a precursor to pepsin. |
| Optimal pH | pH 1.5 to 2.5 (highly acidic) | Activated at low pH, typically below 5 |
| Regulation | Not regulated by direct feedback inhibition | Secretion and activation are tightly regulated by hormonal and neural signals to control digestive processes |
| Location of Action | Active in the stomach, particularly in the gastric lumen | Activated in the stomach for the purpose of initiating protein digestion |