Background: The aggregation of the amyloid-beta peptide (Aβ) in the brain is strongly associated
with Alzheimer´s disease (AD). However, the heterogeneous and transient nature of this process has prevented
identification of the exact molecular form of Aβ responsible for the neurotoxicity observed in this disease.
Therefore, characterizing Aβ aggregation is of utmost importance in the field of AD. Nuclear magnetic resonance
spectroscopy (NMR) is a technique that holds great potential to achieve this goal. However, it requires
the use of specific labels introduced through recombinant expression of Aβ.
Objective: In this paper, we report on a straightforward expression and purification protocol to obtain [U-15N]
and [U-2H,13C,15N] Aβ42.
Method: Aβ42 is expressed fused to Small Ubiquitin-like Modifier (SUMO) protein, which prevents Aβ42 aggregation.
Results: The solubilizing capacity of SUMO has allowed us to design a purification protocol involving immobilized
metal affinity chromatography (IMAC), a desalting step, and two size exclusion chromatography (SEC)
Conclusion: This approach, which does not require the use of costly and time-consuming reversed phase high performance
liquid chromatography (RP-HPLC), offers a much straightforward strategy to those previously described
to obtain [U-15N] Aβ42 and it is the first protocol through which to achieve [U-2H,13C,15N] Aβ42. The peptides obtained
are of high purity and have the required isotope enrichment to support NMR-based structural studies.