7] Measurement of translational and rotational diffusion coefficients by laser light scattering

Abstract

Publisher Summary This chapter describes the measurement of translational and rotational diffusion coefficients by laser light scattering techniques and discusses several applications of these techniques to studies in enzymology, including molecular weight determination, absolute size and shape of enzymes in solution, and observation of conformational changes during protein denaturation. The chapter also describes the problems of sample polydispersity and multiple scattering. Light-scattering techniques have long provided powerful methods for the determination of macromolecular weight, size, and shape. These studies rely upon the accurate determination of the intensity of the light scattered by solutions of macromolecules. Because the lifetimes of the random fluctuations in dielectric constant that produce this scattering are so long compared with the period of the incident light, the spectrum of the scattered light is far too narrow to have been measured before the recent advent of laser light sources, light-mixing spectroscopic techniques, and high resolution Fabry-Perot interferometers. The scattering has thus been referred to as “inelastic” or “quasielastic.”