pepsin

n. enzyme found in gastric juices; medication containing the pepsin enzyme

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.
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Pepsin /pep·sin/ the proteolytic enzyme of gastric juice which catalyzes the hydrolysis of native or denatured proteins to form a mixture of [more]Pepsin - Community and Resources

Noun
1. an enzyme produced in the stomach that splits proteins into peptones
(hypernym) enzyme
(substance-holonym) gastric juice

n. pepsin, enzyme found in gastric juices; medication containing the pepsin enzyme