The structure is a
disulfide rich alpha+beta fold. Bovine pancreatic trypsin inhibitor is an extensively studied model structure. Certain family members are similar to the
tick anticoagulant peptide (TAP, ). This is a highly selective inhibitor of
factor Xa in the blood coagulation pathways. and are arranged to form a twisted two-stranded antiparallel
beta sheet followed by an
alpha helix. The majority of the sequences having this domain belong to the
MEROPS inhibitor family I2, clan IB; the Kunitz/bovine pancreatic trypsin inhibitor family, they inhibit proteases of the S1 family and are restricted to the
metazoa with a single exception:
Amsacta moorei entomopoxvirus, a species of
poxvirus. They are short (about 50 to 60 amino acid residues) alpha/beta proteins with few secondary structures. The fold is constrained by three disulfide bonds. The type example for this family is BPTI (or basic protease inhibitor), but the family includes numerous other members, such as snake venom basic protease; mammalian
inter-alpha-trypsin inhibitors;
trypstatin, a rat mast cell inhibitor of trypsin; a domain found in an alternatively spliced form of Alzheimer's amyloid beta-protein; domains at the
C-termini of the
alpha-1 and
alpha-3 chains of type VI and type VII
collagens; tissue factor pathway inhibitor precursor; and
Kunitz STI protease inhibitor contained in
legume seeds. == Drug development ==