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.