Structure analysis of biological macromolecule in solution by neutron scattering

Solution scattering method has been used as a technique for structure analysis of biological macromolecule in solution for a long time. Here we show the new method to determine ab initio shape and internal structure of biological macromolecules in solution using dummy atoms. The method has been originally developed by Dr. Svergun, and shown to be useful for low resolution structure analysis of biological macromolecule. In the method, a multiphase model of a particle built from densely packed dummy atoms is constructed in the first stage. Simulated annealing is then employed to minimize the difference between the scattering data-sets obtained experimentally and calculated from the multiphase model while minimizing the interfacial area. Validity of the method is assessed in several protein structures, which have been determined by X-ray diffraction at high resolution, by comparing their crystal structures with the solution structures restored by this method. We also compare neutrons and X-rays in terms of structure analyses of biological macromolecule in solution under the high pressure/temperature conditions and various solvent conditions. (author)