Library · Molecule
Pepsin
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Pepsin is the main enzyme in gastric juice that handles proteins. Its job is to cut them into smaller pieces: peptides, which are short chains, and amino acids, which are the individual building blocks.
It leaves the chief cell of the stomach with the safety on, in an inactive form called pepsinogen. What takes the safety off is acid: at the stomach's low pH, pepsinogen cuts itself and turns into active pepsin.
And just as acid switches it on, the lack of acid switches it off. When the stomach contents pass into the duodenum, the first part of the small intestine, the pH rises above 6 and pepsin becomes inactive. Think of a tool that only cuts in acid.
Even so, it is not essential: without pepsin, protein digestion continues thanks to the enzymes from the pancreas.
In brief
Pepsin is the main protein-digesting enzyme in gastric juice: it cuts proteins into peptides and amino acids.
It leaves the chief cell in an inactive form, pepsinogen, and the low pH lets it cut itself and become active.
Once it reaches the duodenum, as the pH rises above 6, it becomes inactive.
A tool that only cuts inside acid and shuts off the moment it leaves.
It is not essential: without it, protein digestion continues with the pancreatic enzymes.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Pepsin, StatPearlsPublished
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