Neutron small-angle scattering of biological macromolecules in solution

In order to get an idea of the possible neutron small-angle scattering experiments with solutions of macromolecules at the high-flux reactor of the Institut Max von Laue-Paul Langevin at Grenoble, aqueous solutions of molecules with molecular weights from about one hundred to several millions have been studied. Changing the contrast by using different H₂O/D₂O mixtures the basic scattering functions could be determined. Zero-angle scattering from neutron and X-ray small-angle scattering experiments are compared. In the case of ferritin the molecular-weight distribution could be determined from the dependence of zero-angle scattering on the solvent. A considerable variation of the square of the radius of gyration R at low contrast was observed. R² turned out to be a linear function of 1/. The slope of the straight line is a measure of the homogeneity of the internal structure. Proton-deuteron exchange reactions have been studied. A time resolution of less than two seconds had been reached with myoglobin and other globular proteins.