Quantitative Analysis of Multiphase Topology from SAXS Data

For any method of structure reconstruction by ab-initio methods additional assumptions must be made. The multipole expansion method of Harrison, Stuhr-MANN, and SvERGUN ([86], Sect. 5.3 [101], Chap. 6) assumes homogeneous internal density. The shape of the scattering curve is fitted by varying the envelope of the particle. 

A programming package PRIMUS for the evaluation of isotropic SAXS patterns is offered by Svergun [196]. Although the focus is on biopolymers, it can also evaluate general particle scattering. 

Power and Limits of the SAXS Methods. This field of SAXS is in competition with the field of protein crystallography. The spatial resolution of the SAXS method is limited ( 0.5 nm), whereas structures determined by protein crystallography are exact up to fractions of Angstrpms. On the other hand, the protein crystallography is unable to study living proteins under almost physiological conditions. Moreover, kinetic processes can be monitored by SAXS but cannot be studied by means of protein crystallography. 

If mixtures and assemblies of different kinds of particles are studied, a shape reconstruction is no longer possible from a study of isotropic SAXS in solution [188]. 

7 Quantitative Analysis of Multiphase Topology from SAXS Data 

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