soybean trypsin inhibitor (STI)-like domain, beta-trefoil fold, found in Bauhinia bauhinioides Kunitz-type serine protease inhibitor BbKI and similar proteins
This subfamily includes Bauhinia bauhinioides BbKI, BbCI, Bauhinia rufa BrTI, and similar proteins. BbKI inhibits bovine trypsin, human plasma kallikrein and plasmin, and weakly inhibits bovine chymotrypsin. BbCI inhibits cruzipain, a cysteine proteinase from Trypanosoma cruzi. It also inhibits cathepsin L, a cysteine proteinase with high homology to cruzipain, but not cathepsin B, papain, bromelain, or ficin. BrTI acts as an inhibitor of trypsin and human plasma kallikrein. It does not inhibit chymotrypsin, porcine pancreatic elastase, human neutrophil elastase, coagulation factor Xa, human thrombin, porcine pancreatic kallikrein or plasmin. Members of this subfamily contain an STI-like domain with a beta-trefoil fold, which is characterized by 12 beta strands folded into three similar trefoil subdomains (alpha, beta, and gamma) associated to give an overall structure with pseudo-3-fold symmetry.
Jiyao W et al.(2023). "The conserved domain database in 2023.",