The suppression of removal of the formation of amyloid or neurofibrillary tangles is also crucial in the treatment of alzheimers disease. Beta-amyloid is generated in normal people as well . however, unlike in alzheimer’s patients, amyloid precursor protein undergoes a sequential cleavage first by α-secretase and then by γ-secretase, generating a water-soluble and nonpoisonous peptide different from beta-amyloid. In contrast, amyloid or beta-amyloid in alzheimers patient is a insoluble 4-kDa peptide that is generated when amyloid precursor protein is cleaved by β- and γ-secretase. γ-secretase is a multiprotein complex comprising presenilin 1 and 2, which generates beta-amyloid by cleaving the transmembrane domain of amyloid precursor protein after its cleavage by β-secretase. For the most part, beta-amyloid generates beta-amyloid40 which consists of 40 amino acids, but, due to a large number of cleavage sites, it occasionally generates a small amount of beta-amyloid42, which is more likely to form fibrils more resistant to decomposition, making it more toxic to neurons compared to beta-amyloid40.