Protein envelope shape and folding in solution
SAXS also complements other techniques in structural biology. For instance, a solution scattering curve can be readily calculated using a set of atomic coordinates derived from macromolecular crystallography, providing a means of comparing solution structures with crystal structures. Structural changes induced by ligand binding, or changes in other chemical or physical environment, can be monitored using solution scattering and interpreted based on high-resolution structures derived from other techniques. Solution scattering can help model a large molecular complex whose over-all structure is unknown but where the structures of individual components are available.
Small-angle X-ray scattering (SAXS) is a small-angle scattering technique by which nano-scale density differences in a sample can be quantified. This means that it can determine nano-particle size distributions, resolve the size and shape of (mono-disperse) macro-molecules, determine pore sizes, characteristic distances of partially ordered materials, and much more. This is achieved by analyzing the elastic scattering behavior of X-rays when traveling through the material, recording their scattering at small angles (typically 0.1 - 10°). SAXS is used for the determination of the microscale or nanoscale structure of particle systems in terms of such parameters as averaged particle sizes, shapes, distribution, and surface-to-volume ratio.