Quasi Elastic Light Scattering from Macromolecules in Solution

Abstract

The problem of the determination of the size of macromolecules in solution plays an important role in biochemical studies. Many fundamental processes, like protein denaturation, aggregation, formation of micellar compounds, etc. are associated with changes in size. It is therefore understandable that experimentalists have tackled this problem in a variety of ways. Information on the size of a macromolecule can be gained by performing measurements of the angular anisotropy of the scattered radiation¹. Indeed when the diameter of the macromolecule becomes an appreciable fraction of the wavelength of light, the intensity of the light scattered near the forward direction is higher than in the backward direction. This difference in scattered intensities increases with the diameter of the macromolecule and the study of the actual distribution of the scattered intensity as a function of angle yields precise information on the diameter of the macromolecule. This technique however is limited to fairly large macromolecules and therefore a wide class of systems cannot be studied since the intensity angular anysotropy they produce is too small to be evaluated with any confidence.