Determination of domain structure of proteins from X-ray solution scattering

An ab initio method for building structural models of proteins from x-ray s olution scattering data is presented. Simulated annealing is employed to fi nd a chain-compatible spatial distribution of dummy residues which fits the experimental scattering pattern up to a resolution of 0.5 nm. The efficien cy of the method is illustrated by the ab initio reconstruction of models o f several proteins, with known and unknown crystal structure, from experime ntal scattering data. The new method substantially improves the resolution and reliability of models derived from scattering data and makes solution s cattering a useful technique in large-scale structural characterization of proteins.