Crystallization and preliminary X-ray diffraction analysis of a thermostable endo-1,5-α-L-arabinanase from Bacillus thermodenitrificans TS-3

A thermostable endo-1,5-α-L-arabinanase ABN-TS from Bacillus thermodenitrificans TS-3 with a molecular weight of 35 kDa was crystallized by the hanging-drop vapour-diffusion method using sodium citrate as a precipitant. The crystals were loop-mounted in a cryoprotectant solution containing 28%(w/v) sucrose and 1 M sodium citrate pH 6.0 and flash-cooled. Sucrose was selected as the most suitable cryoprotectant. The crystal belonged to the orthorhombic space group P2₁2₁2₁, with unit-cell parameters a = 40.3, b = 77.8, c = 89.7 Å. The calculated V_M based on one molecule per asymmetric unit was 2.0 ų Da⁻¹. A complete data set from a frozen crystal was collected to 1.9 Å resolution using synchrotron radiation at SPring-8. A molecular-replacement solution was obtained using the structure of α-arabinanase 43A from Cellvibrio japonicus.