beta-Amyloid 40 (human) (rec.)

beta-amyloid (Abeta) peptides result from the proteolytic cleavage of beta-amyloid precursor protein (APP) which is encoded by a gene located on chromosome 21. Abeta is produced by two proteases (beta- and gamma- secretase) and has vary forms (39- and 43-mer peptides). Abeta40 and Abeta42 peptides are major constituents of the plaques and tangles that occur in Alzheimer’s disease(AD). Abeta42 plays a critical role in the pathogenesis of AD since its aggregative ability and neurotoxicity are much greater than these of Abeta40. Abeta42 oligomers initially formed as a seed accelerate the aggregation of Abeta40 to form the amyloid plaques that eventually lead to the neurodegeneration (amyloid cascade hypothesis). Abeta40 also serves as an antioxidant molecule by quenching metal ions and inhibiting metal-mediated oxygen radical generation.