Direct Comparison of the Crystal and Solution Structure of Glucose/Xylose Isomerase from Streptomyces rubiginosus

Glucose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5.) catalyses the isomerization reaction of glucose and xylose. The small angle X-ray scattering (SAXS) data of glucose/xylose isomerase from Streptomyces rubiginosus were recorded for protein solution using synchrotron radiation. The experimental data were compared with theoretical scattering calculated on the basis of the known crystal structure (PDB code: 1OAD). The radius of gyration measured by SAXS (RG=3.30 nm) was almost identical and the maximum dimension in the distance distribution function was by about 2.5 % lower than the corresponding values calculated on the basis of the crystal structure.