How to prepare Alzheimer's amyloid-β(1-42) oligomer samples with sufficient quantity and quality for biophysical and solid-state NMR measurements.

This chapter outlines a protocol for preparing an oligomeric amyloid-β peptide (AβO) for solid-state NMR structural studies. This protocol was developed for the 42-amino acid isoform Aβ(1-42), which is a focus due to its pathological link to Alzheimer's disease (AD). This peptide is highly aggregation-prone and would rapidly form fibrils without special efforts to direct aggregation towards AβO. Our protocol includes separation of Aβ(1-42) monomers from fibril seeds that are typically present in synthetic preparations, exposure of monomers to detergent micelles of sodium dodecyl sulfate (SDS), and separation of oligomers from monomers. Separation of distinct aggregated states of Aβ(1-42) is performed using size-exclusion chromatography. Removal of SDS is performed by dialysis. Solid-state NMR rotors can be loaded via ultracentrifugation or lyophilization.