Purification, crystallization and preliminary X-ray crystallographic analysis of xylose reductase from Candida tropicalis

Xylose reductase (XR), which requires NADPH as a co-substrate, catalyzes the reduction of d-xylose to xylitol, which is the first step in the metabolism of d-­xylose. The detailed three-dimensional structure of XR will provide a better understanding of the biological significance of XR in the efficient production of xylitol from biomass. XR of molecular mass 36.6 kDa from Candida tropicalis was crystallized using the hanging-drop vapour-diffusion method. According to X-ray diffraction data from C. tropicalis XR crystals at 2.91 A resolution, the unit cell belongs to space group P31 or P32. Preliminary analysis indicated the presence of four XR molecules in the asymmetric unit, with 68.0% solvent content.