Protein preparation, crystallization and preliminary X-ray analysis of imidazolonepropionase from Bacillus subtilis

Imidazolonepropionase (EC 3.5.2.7) is the third enzyme of the histidine degradation pathway that has been conserved from bacteria to eukaryotes. The enzyme is the only one with unknown three-dimensional structure in this pathway. In this work, Bacillus subtilis imidazolonepropionase (HutI) was expressed in E. coli and purified to homogeneity. After thrombin digestion, high quality crystals were obtained by hanging-drop vapor diffusion method. The best crystal diffracted to 2.0 Å and belonged to the space group P21 with unit-cell parameters a = 57.73 Å, b = 106.34 Å, c = 66.47 Å, β = 89.93 °.