An Efficient Method of Expression and Purification of Amyloid-Beta (Aβ) Peptide from E. coli.

Amyloid-beta (Aβ) aggregation into soluble oligomers and fibril formation are associated with Alzheimer's disease (AD) pathogenesis. Aβ is the major form of the Aβ peptide present in neuritic plaques and shown to be neurotoxic both in vivo and in vitro. However, understanding the mechanism of its toxicity, aggregation, and other biochemical properties is limited because of its difficult production (recombinant or synthetic) and irreproducibility issues attributed to batch-to-batch preparation differences. Chemically synthetic Aβ is now well established, but it always introduces up to 5% D-isomers along with its L-isomeric form, and thus it is not fruitful for biochemical/structural studies. Here, we optimized an efficient published method for expression and purification of Aβ upon overexpression in Escherichia coli (E. coli) that provides a satisfactory yield as well as minimizes the variability between batch preparations. With the present protocol, ~7-8 mg/liter of unlabeled peptide and ~3.5-4 mg/liter for C,N-labeled (double-labeled) Aβ were obtained.