– Amyloid β-Protein (3-42) TFA is a precursor of the Pyr peptide. The core of amyloid plaques in Alzheimer’s disease is composed of pyroglutamate-modified Aβ (pEAβ) (3-42). Interestingly, pEAβ (3-42) accelerates the aggregation of Aβ(1-42), whereas Aβ(1-42) significantly slows both the primary and secondary nucleation of pEAβ(3-42).