β-Amyloid peptide (1–42) (Aβ42) is a 42-amino-acid peptide that is widely recognized as a key pathogenic species in Alzheimer’s disease (AD). Compared with shorter Aβ isoforms, Aβ42 exhibits markedly enhanced neurotoxicity and aggregation propensity, and is considered a principal initiator of amyloid plaque formation in the AD brain.

Aβ42 is produced by sequential proteolytic cleavage of the amyloid precursor protein (APP), a type I transmembrane protein encoded by the APP gene on human chromosome 21. Following initial β-secretase cleavage, γ-secretase processing at alternative C-terminal sites generates multiple Aβ species, of which Aβ42 represents a less abundant but highly pathogenic form.

Structurally, Aβ42 contains two additional hydrophobic residues at the C-terminus relative to Aβ40. These residues significantly increase β-sheet formation, molecular self-association, and fibril stability. As a result, Aβ42 rapidly assembles into soluble oligomers, protofibrils, and mature amyloid fibrils, species that are strongly associated with synaptic dysfunction, neuronal toxicity, and disease progression.

TDA-1204-100-datasheet.pdf