Crystallization and preliminary studies of lima bean trypsin inhibitor

Crystals of lima been trypsin inhibitor (LBTI) were obtained by using the vapor phase equilibration technique with sodium/potassium tartrate as the precipitating agent. The space group was determined to be cubic, I2(1)3 with a = 110.2. A These crystals diffract to about 1.9 A resolution. Preliminary analysis of self-rotation maps (calculated from native x-ray intensity data) suggests the presence of two monomers in the asymmetric unit. LBTI is very thermostable and retains activity even after boiling for 10 minutes. This property is exploited as part of its purification procedure.