Submitted to: Nonlinear Computer Modeling of Chemical and Biochemical Data
Publication Type: Book / Chapter
Publication Acceptance Date: 5/4/1995
Publication Date: N/A
Citation: Interpretive Summary: Book Chapter interpretive summary is not required.
Technical Abstract: Chapter 9 deals with the use of nonlinear regression models for the analysis of the small angle X-ray scattering data from proteins in solution and for calculating molecular parameters such as the radius of gyration, hydrated volume, molecular weight, axial ratio of the particle, electron density, degree of hydration and distance distribution function along with their corresponding errors. The theoretical considerations of small angle X-ray scattering are presented in detail and the equations to be used with nonlinear regression analysis are shown. The use of the traditional linearized Guinier plot is shown to have serious drawbacks in analyzing data leading to large nonrandom errors in derived molecular parameters. A better model is to use multiple Gaussian shapes centered at zero angle as the function to fit the data using nonlinear regression analysis. Small angle Xray scattering data on the solution structure of Bovine Casein in micellar and submicellar conditions is presented. It is shown by nonlinear regression analysis that the derived molecular parameters describe a nonhomogeneous particle. This information could not be ascertained if the Guinier plot was used.