Final answer:
Beta Amyloid peptide (1-42) is produced from APP through enzymatic cleavage by β- and γ-secretases. Normal conditions allow for the clearance of excess peptides, but unregulated formation can lead to beta amyloid plaques in Alzheimer's disease.
Step-by-step explanation:
The beta Amyloid peptide (1-42) is generated from the amyloid precursor protein (APP) through enzymatic cleavage involving two specific enzymes. The process begins with the cleavage of APP by an enzyme known as β-secretase, which cuts the extracellular part of APP. Following this initial cleavage, another enzyme called γ-secretase, further cleaves the remaining part of the protein to ultimately release the Aβ peptide, which can then aggregate to form plaques associated with Alzheimer's disease. Under normal circumstances, any excess Aβ peptides are digested and cleared out to prevent plaque formation. However, in Alzheimer's disease, the formation of these peptides is unregulated, which leads to accumulation and formation of the beta amyloid plaques seen in the disease. It is also noted that normal prion protein (PrPc) can bind to Aβ peptides and prevent aggregation, whereas mutant prion protein (PrPsc) can inhibit this function, promoting plaque formation.