Everything about Pepsin totally explained
Pepsin is a
digestive protease released by the
chief cells in the
stomach that functions to degrade food
proteins into
peptides.
According to
American Heritage Dictionary, pepsin derives from the
Greek word
pepsis, meaning
digestion (
peptein: to digest).
Pepsin was discovered by
Theodor Schwann in
1836. It was the first animal
enzyme to be discovered.
Precursor
Pepsin is
expressed as a pro-form
zymogen,
pepsinogen, whose
primary structure has an additional 44
amino acids.
In the stomach,
chief cells release pepsinogen. This zymogen is activated by
hydrochloric acid (HCl), which is released from
parietal cells in the stomach lining. The hormone
gastrin and the
vagus nerve trigger the release of both
pepsinogen and HCl from the stomach lining when food is ingested. Hydrochloric acid creates an acidic environment which allows pepsinogen to unfold and cleave itself in an
autocatalytic fashion, thereby generating pepsin (the active form). Pepsin cleaves the 44 amino acids from pepsinogen to create more pepsin. Pepsin will digest up to 20% of ingested carbon bonds by cleaving preferentially after the N-terminal of aromatic amino acids such as
phenylalanine and
tyrosine. It won't cleave at bonds containing
valine,
alanine, or
glycine. Peptides may be further digested by other proteases (in the
duodenum) and eventually absorbed by the body.
Pepsin is stored as pepsinogen so it'll only be released when needed, and doesn't digest the body's own proteins in the stomach's lining.
Pepsin functions best in acidic environments and is often found in an acidic environment, particularly those with a pH of 1.5 to 2.
Pepsin is said to have an optimum temperature between 37°C and 42°C in humans.
Further Information
Get more info on 'Pepsin'.
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