Small angle x-ray study on the structure of active and inactive ribulose bisphosphate carboxylase from Alcaligenes eutrophus. Evidence for a configurational change.

Two small angle x-ray scattering curves have been obtained from active and inactive ribulose 1,5-bisphosphate carboxylase from Alcaligenes eutrophus. The radius of gyration was calculated to be R = 47.8 +/- 0.1 nm for the active enzyme and R = 49.2 +/- 0.1 nm for the inactive enzyme. The maximum particle dimension amounts to 13.5 +/- 0.5 nm for the active and 15.7 +/- 0.5 nm for the inactive enzyme. A model of the active carboxylase is presented. It is in good agreement with models derived from electron microscopical data. Model calculations for the inactive enzyme show some evidence for a configurational change.

Small-angle X-ray study of the 50 S ribosomal subunit of Escherichia coli. A comparison of different models.

A small angle X-ray scattering curve obtained from Escherichia coli 50 S subunits has been compared with the scattering curves calculated for three-dimensional 50 S models proposed by various authors. The one proposed by Lake, Stöffler and Vasiliev showed to some extent a good agreement with our experimental data. Calculating a large number of possible particle structures we found a model which optimally fits our experimental curves, but it's two-dimensional projections differ a little from the projections of 50 S subunits observed by electron microscopy.