In the process of natural selection there has been a trade-off between the optimal efficacy and stability of proteins, most proteins being prone to denaturation in aqueous solution under ambient conditions. Aggregation often makes such conformational changes irreversible. This presentation discusses the application of light scattering techniques to the analysis of changes in protein conformation and oligomeric state.

A major advantage of applying light scattering technologies to protein aggregation analysis is their high sensitivity to large particles. The application of Static Light Scattering (SLS), Dynamic Light Scattering (DLS) and Electrophoretic Light Scattering (ELS) to the monitoring of the earliest stages of protein aggregation is described. Applications outlined include the elucidation of the mechanism of amyloidosis and investigations into the effect of arginine on aggregation. The use of interaction parameters derived using these techniques, both to estimate aggregation propensity and to investigate the nature of protein-protein interactions, is explained. The use of DLS as a sensitive, simple and inexpensive means of carrying out cuvette based protein binding studies is also outlined, as is the application of the technique to the analysis of protein conformational changes.

The use of separation techniques, such as Size Exclusion Chromatography (SEC), to improve the resolution of light scattering measurements is also described. Such separation allows absolute measurement of the size and mass of the various components of impure protein mixtures without the use of protein markers. Emphasis is placed on the use of SEC in combination with various detectors as a means of assessing the morphology of both small peptides and large aggregates.

Finally, the cutting edge use of DLS-Microrheology as a means of monitoring changes in protein intrinsic viscosity during denaturation, and alterations in the elastic modulus during aggregation, is outlined.