Bovine Pancreatic Trypsin Inhibitor

Bovine pancreatic trypsin inhibitor, or BPTI, is a protein found in many tissues throughout the body. BPTI inhibits several of the serine protease proteins such as trypsin, kallikrein, chymotrypsin, and plasmin. BPTI is a member of the pancreatic trypsin inhibitor (kunitz) family, which is a family of serine protease inhibitors. These proteins usually have conserved cysteine residues that participate in forming disulfide bonds. Shown here in blue are the three disulfide bonds in BPTI. They are as follows: Cys5-Cys55, Cys14-Cys38, and Cys30-Cys51.
BPTI is a monomeric polypeptide containing 58 amino acid residues. The picture shown here is colored by secondary structure. All beta sheets are colored hot pink. The two alpha helices are colored differently: Green= a right-handed alpha helix, gold= a 310 alpha helix. 

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