C-terminal Kunitz domain of inhibitor ornithodorin and similar proteins
The Kunitz inhibitor ornithodorin is a highly selective and potent thrombin inhibitor isolated from blood sucking soft tick Ornithodoros moubata. Ornithodorin is a two-domain protein that resembles the tick anticoagulant peptide (TAP) isolated from the same organism, especially the N-terminal domain; this model contains the C-terminal domain. While the N-terminal domain binds to the active site of thrombin, this C-terminal domain binds at the fibrinogen recognition exosite. The structure of this domain is similar to those of Kunitz-type proteinase inhibitors such as BPTI (bovine pancreatic trypsin inhibitor), showing an alpha/beta fold with irregular secondary structure stabilized by three disulfide bonds.
Jiyao W et al.(2023). "The conserved domain database in 2023.",