Examples of neutron small angle scattering experiments of living body substance by using KENS-SAN

As demonstration experiments, the neutron small angle scattering experiments on purple membrane and collagen were carried out. In the experiment of the purple membrance, the primary the secondary and the tertiary Bragg reflections were observed. A conceptual diagram of the reciprocal lattice space is presented. The wavelength dependence of the structure factor of the primary reflection was obtained. The small angle scattering experiment of collagen showed the regularity of 670 x 10-8cm in the fibre direction. The collagen molecule assemblies appeared at intervals of 670 x 10-8cm. The structure of nucleosome was investigated by the neutron small angle scattering experiment. When the ion intensity was varied, the radius of rotation was measured by the experiment. A Guinier plot of nucleosome solution (1 percent) in D2O (65 percent) - H2O (35 percent) with 10 mM of Nacl was obtained. The same kind of measurement was made for the 1 percent nucleosome in 100 percent D2O, and compared with the experiment of 65 percent D2O. Better accuracy was obtained for the experiment of 100 percent D2O. A phase transition of the molecular structure was found. (Kato, T.)