Benefit of SAXS over normal xray analysis?

[philip041]

I think I understand correctly that small angle xray scattering, (SAXS), has an advantage over normal xray diffraction techniques in that you can analyse crystals with higher spacings, (if you look at BRaggs law). However isn't single crystal xray diffraction used on protein crystals all the time and don't these have large spacings? Any suggested reading, I need to understand xray analysis of protein crystals?

Cheers

 

[tnemelc]

SAXS is not used on protein crystals but on protein in solution. The resolution is much lower, no information is known about the position of individual atoms, but the size and the shape can be determined.
The advantage of SAXS is that the protein are in solution, close to physiological conditions. One don't need any crystal, and one can check if the structure of a protein in solution is the same as the one in a crystal.
SAXS is also very useful to determine the conformation of oligomeric construction.
More informations can be found here: http://en.wikipedia.org/wiki/Biological_small-angle_X-ray_scattering