A major area of Biochemistry has become studying the interactions of proteins and other biological macromolecules in large complexes, e.g. transcription complexes, nucleosomes, ribosomes, etc. These complexes are dynamic species that modify their structure as their biochemical function is modulated by various environmental parameters. Characterizing these complexes and their conformational changes is difficult by many of the tools of structural biology as their prohibitive size makes most approaches impractical. Dynamic and static laser light scattering offer the potential to provide coarse structural characterization of these large complexes while also permitting changes induced by external factors to be quantified. Coupling the light scattering instrument to a size exclusion chromatography system permits the additional separation and hydrodynamic characterization of the complex immediately prior to the light scattering analysis. This can be an essential aspect of the integrated instrument as light scattering analysis of polydisperse systems requires complex analysis that is highly dependent on the model. A second area of concentrated interest at Case Western Reserve University is in characterizing the aggregation of proteins involved in pathogenic amyloid formation including the Abeta peptide of Alzheimer's Disease, (alpha-synuclein found in Lewy bodies, and prion proteins that trigger spongiform encephalitis. In the aggregation of these proteins, early events in the formation of oligomers are crucial to the eventual formation of insoluble amyloid. Again characterizing these oligomers is difficult because they are rarely the predominant form present in solution but exist at low concentrations in a slow equilibrium or steady state of aggregate formation. The availability of a high resolution gel permeation chromatography system integrated with an online laser light scattering detector will permit the individual characterization of the different oligomeric forms of these amyloid forming proteins. Again the immediate detection of the separated oligomer is important to avoid the necessity of deconvoluting the contributions arising from a polydisperse solution. A combination Multi-Angle Laser Light Scattering (MALLS) detector and quasi elastic light scattering (QELS) detector permit the determination of both the rms radius (RG) and the hydrodynamic radius (RH), respectively, along with the molecular weight of an eluate. Funds for the acquisition of the SEC system integrated with the combination light scattering detectors are requested for inclusion in the CWRU protein characterization facility.
