Pepsin, was, in the 18th century, the first
enzyme to be discovered and the second enzyme to be
crystalized. It is an enzyme created by the
stomach expressely for breaking down
proteins. Now, the problem arises as to how to create an enzyme for breaking down proteins without destroying the
cell that creates it, which is largely protein based. Pepsin is created with an extra 44
amino-acids bonded to its
active site, in a form called
pepsinogen. Once pepsinogen is escorted out of the cell and into the highly acidic
digestive fluids,
HCL acid cuts off the extra 44 amino-acids, thereby activating pepsin to do its duty of breaking apart proteins.
Stats:
Molecular Weight: 35,000+ AMU
pH optimum: 1 - 4
Stability: Pepsin is stable up to a temperature of 60 degrees Celsius, and is irretrivably deactivated at a pH of 6
Pepsin types: A,B,C,D, With A being a supermajority.
Pepsin will not cleave at places bonded by valine, alanine or glycine.
Sources:
- http://www.rcsb.org/pdb/molecules/pdb12_1.html
- http://prowl.rockefeller.edu/recipes/sproteas/pepsin.htm
- http://www.worthington-biochem.com/priceList/P/Pepsin.html
- http://www.worthington-biochem.com/manual/P/PM.html