The complex formed between the antistasin-type inhibitor bdella­stasin and porcine β-trypsin has been crystallized in the tetragonal crystal form of space group P4₁2₁2 and solved and refined to 2.7 Å resolution. A comparison with the porcine β-trypsin–bdellastasin complex of the enantiomorphic space group P4₃2₁2 and other known crystal structures of porcine β-trypsin–macromolecular inhibitor complexes suggests that deamidation, isomerization and racemization of trypsin residue Asn115 is the key step in its crystallization.

The synthetic gene of the amino-terminal domain of the antistasin-type inhibitor ghilanten (ghilanten-D1) from H. ghilianii was constructed, expressed in the methylotrophic yeast P. pastoris and purified by heparin–Sepharose chromatography. Recombinant ghilanten-D1 has been crystallized in complex with porcine β-trypsin in three different-looking but isomorphous crystal forms, each belonging to the orthorhombic space group P2₁2₁2₁.