Glucose isomerase from Streptomyces rubiginosus – potential molecular weight standard for small-angle X-ray scattering

Stability of solutions of glucose isomerase from Streptomyces rubiginosus on long-term storage and on exposure to synchrotron radiation has been studied by the small-angle X-ray scattering (SAXS) method. The values of the radii of gyration and forward scattering do not change significantly on storage and on exposure to synchrotron radiation. The mean value of the radius of gyration characterizing glucose isomerase is R_G = 3.27 ± 0.02 nm. For comparison, a SAXS study of monodispersive and aggregated bovine serum albumin (BSA) has been carried out. The results show that glucose isomerase could be a more stable molecular weight standard for SAXS than BSA.