Purification of recombinant Aβ(1-42) and pGlu-Aβ(3-42) using preparative SDS-PAGE.

Recombinant expression and purification of amyloid peptides represents a common basis for investigating the molecular mechanisms of amyloid formation and toxicity. However, the isolation of the recombinant peptides is hampered by inefficient separation from contaminants such as the fusion protein required for efficient expression in E. coli. Here, we present a new approach for the isolation of highly purified A(1-42) and pGlu-A(3-42), which is based on a separation using preparative SDS-PAGE. The method relies on the purification of the A fusion protein by affinity chromatography followed by preparative SDS-PAGE under reducing conditions and subsequent removal of detergents by precipitation. The application of preparative SDS-PAGE represents the key step to isolate highly pure recombinant A, which has been applied for characterization of aggregation and toxicity. Thereby, the yield of the purification strategy was >60%. To the best of our knowledge, this is the first description of an electrophoresis-based method for purification of a recombinant A peptide. Therefore, the method might be of interest for isolation of other amyloid peptides, which are critical for conventional purification strategies due to their aggregation propensity.