Beta-amyloid production results from cleavage in the extracellular domain of APP by the beta-secretase (BACE1) , which results in the production of the APP C-terminal fragment C99. This fragment is further cleaved by the gamma-secretase at residues 40-42 to produce beta-amyloid 40 and 42 peptides. Beta-amyloid aggregation and neuritic plaque formation are pathologic hallmarks of Alzheimer disease. This peptide corresponds to the human beta-amyloid 1-42 peptide.Human: Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-Leu-Val-Phe-Phe-Ala-Glu-Asp-Val-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-Gly-Val-Val-Ile-Ala or H-DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA-OH

β -淀粉样蛋白（amyloid β-protein，Aβ）分子量约4kDa，由β淀粉样前体蛋白(β-amyloid precursor protein,APP)水解而来，由细胞分泌，在细胞基质沉淀聚积后具有很强的神经毒性作用。β 淀粉样蛋白( amyloid-β，Aβ) 是由淀粉样前体蛋白( amyloid precursor protein，APP) 经 β-和 γ-分泌酶的蛋白水解作用而产生的含有 39～43 个氨基酸的多肽。它可由多种细胞产生，循环于血液、脑脊液和脑间质液中，大多与伴侣蛋白分子结合，少数以游离状态存在。人体内 Aβ最常见的亚型是 Aβ1～ 40 和 Aβ1～ 42。