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How does pepsin break down proteins in the stomach?
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digestion
The human digestive system as seen from the front.
Pepsin is a powerful enzyme responsible for the partial degradation of dietary proteins within the stomach.1
The process functions as follows:
- Activation: Glands in the stomach lining secrete an inactive precursor called pepsinogen. When mixed with hydrochloric acid in the stomach, pepsinogen is rapidly converted into its active form, pepsin.12
- Optimal Conditions: The digestive activity of pepsin is most effective in the highly acidic environment of the stomach, specifically at a pH of 1.5β2.5.1
- Mechanism: Pepsin performs proteolysis, a process that breaks down complex protein molecules into smaller units known as peptides.13
- Outcome: This action is only a partial degradation. Once the partially digested peptides move into the small intestine, the gastric acids are neutralized, rendering pepsin ineffective. Further breakdown into amino acids is then carried out by pancreatic enzymes.13