The molecular architecture of native GroEL has been studied by solution X-ray scattering. The radius of gyration for the native molecule was estimated to be 66.0 Å in 50 mM Tris-HCl, 100 mM KCl at pH 7.5 and 25°C. The maximum dimension was estimated to be 170 Å, based on the pair distance distribution function. A cylindrical structure or two heptameric rings was found to be the best for native GroEL among structures examined by using a multi-sphere model analysis in which the radius of constituent sphere was 6 Å. The results of the model analysis show that the radius of GroEL is 68.0 Å and the height is 150.7 Å. Unexpectedly, the central penetrating hole through GroEL was not confirmed in the best-fit structure.
