NMR spectroscopy of MAβ. 15N HSQC NMR spectra of MAβ(1–40) (A, blue), Aβ(1–40) (A, red), MAβ(1–42) (B, blue) and Aβ(1–42) (B, red) at 5°C at 800 MHz. The spectra illustrate the purity of the recombinantly expressed peptides. The chemical shifts and sharp NMR resonances indicate that the peptides exist in disordered monomeric conformations. Resonances of Aβ(1–40) that are displaced as a consequence of the presence of the N-terminal methionine in MAβ(1–40) are indicated. Assignments were obtained from literature spectra [35, 52].