Trypsin

Trypsin, a member of the serine protease family, is produced in the pancreas and found in the digestive tracks of vertebrates. To avoid pancreatic self-degradation, trypsin is synthesized as trypsinogen, a zymogen. Cleavage by enteropeptidase allows tryspin to enter its active form. As a serine protease, trypsin contains a serine residue in its active site.

Structure

The trypsin structure displayed is a mutant form isolated from a bovine pancreas. It contains 58 amino acid residues as well as an altered binding loop. To follow the primary structure (amino acid sequence) of Trypsin, click here. Begin at the N-terminus (blue) and move toward the C-terminus (red).

The secondary structure of Trypsin consists of two alpha helices (light green) and two beta sheets (peach). Hydrophobic interactions - mainly the hydrophobic collapse - significantly contribute to both secondary and tertiary structure. This structure shows that the majority of the residues are non-polar/hydrophobic (maroon). These residues tend to congregate on the interior of the structure while polar/hydrophilic residues (blue) remain on the exterior. This orientation allows polar molecules to maximize interaction with water and other polar molecules while non-polar molecules minimize such interactions. Adding water molecules to the model, the polar/non-polar interactions can be seen.

Stability

The yellow and red molecules represent SO4 (2-) moieties which are not part of the traditional trypsin structure; they were added during crystallization to freeze Trypsin in a specific conformation. Fix THIS. they bind at active site

Function

The reaction catalysed by Enteropeptidase:

trypsinogen → trypsin + hexapeptide

Val--(Asp)4--Lys--Ile--Val~ (trypsinogen) → Val--(Asp)4--Lys (hexapeptide) + Ile--Val~ (trypsin)

Enteropeptidase cleaves after Lysine if the Lys is preceded by four Asp and not followed by a Pro. Source ^ "Enterokinase, light chain (P8070), Proteases, NEB". https://www.neb.com/nebecomm/products/productP8070.asp. Retrieved 2007-10-04.

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