Pepsin is derived from the Greek word "pepsis" which means digestion.
Pepsin is an enzyme secreted by gastric chief cells that line the surface of the stomach. This enzyme is first in a series of enzymes that digest proteins. Pepsin is constructed first inside the cell with an exrta 44 amino acids in the form of Pepsinogen. These extra 44 amino acids block the large active site cleft and prevent the enzyme from immediately starting to digest the cell's own proteins (Goodsell 2000).
The first enzyme to be discovered was pespin by Theodor Schwann in 1836. Pepsin was also the second ezyme to be crystalized (Weisstein 1996).
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