Pepsin

Definition

Pepsin is an enzyme in the stomach that breaks down proteins into smaller peptides. It is activated from its precursor, pepsinogen, in the acidic environment of the stomach.

5 Must Know Facts For Your Next Test

1. Pepsinogen is secreted by chief cells in the stomach lining and converts to pepsin in acidic conditions.
2. Pepsin functions optimally at a pH of around 1.5 to 2.
3. It breaks down proteins by cleaving peptide bonds, primarily after aromatic amino acids like phenylalanine, tryptophan, and tyrosine.
4. The activity of pepsin is crucial for initiating protein digestion before it continues in the small intestine.
5. Pepsin's activity can be inhibited by antacids or medications that reduce stomach acidity.

Review Questions

• What type of biomolecule does pepsin specifically break down?
• How is pepsin activated from its inactive form?
• Why is the acidic environment of the stomach important for pepsin function?

Related terms

Pepsinogen:

An inactive precursor of pepsin secreted by chief cells in the stomach.

Chief Cells: Cells located in the lining of the stomach that secrete pepsinogen.

Gastric Acid:

Hydrochloric acid (HCl) present in gastric juice that provides an acidic environment for enzymes like pepsin to function.