Crystallization and preliminary crystallographic characterization of the N-terminal Kunitz domain of boophilin

Boophilin is a tight-binding thrombin inhibitor composed of two canonical Kunitz-type domains in a tandem arrangement. Thrombin-bound boophilin can inhibit a second trypsin-like serine proteinase, most likely through the reactive loop of its N-terminal Kunitz domain. Here, the crystallization and preliminary crystallographic analysis of the isolated N-terminal domain of boophilin is reported. The crystals belonged to the orthorhombic space group P2₁2₁2₁ and diffracted to beyond 1.8 Å resolution using a sealed-tube home source and to 0.87 Å resolution at a synchrotron source.