Purification & Aggregates

Scientists carrying out detailed mechanistic studies of proteins and their biological function can't afford to work with poor quality material. Light scattering offers two distinct means of assessing the quality and purity of protein samples: dynamic light scattering (DLS) and size exclusion chromatography coupled to multi-angle light scattering (SEC-MALS).

DLS is an excellent means for obtaining rapid, qualitative estimates of aggregation and impurities in a protein solution, with minimal sample consumption – as little as 2 µL. No separation step is required; just pipette a few drops into a microcuvette or microwell plate, and you'll have a size distribution within seconds. Large sub-micron aggregates in particular are readily identified with DLS, as well as the presence of soluble aggregates through the polydispersity parameter. Batch (unfractionated) DLS even allows for recovery of precious samples, even if only a few microliters were used in the measurement.

While DLS measures coarse distributions of size (hydrodynamic radii), you may need to distinguish and quantify small aggregates such as dimers and trimers, or obtain accurate identification of impurities or degradants. SEC-MALS performs true separations with absolute molar mass measurements in order to obtain reliable indications of just which proteins and degradants are present in solution.