Purification and cloning of monkey proteases involved in the processing of the β-amyloid precursor protein

We investigated adult and aged monkey brain to identify a serine protease able to generate the N-terminus of the beta -protein. We looked for a serine protease because of the presence of ACT in amyloid deposits, the KPI domain of APP; both of which are serine protease inhibitors, and because the sequence of the N-terminus of the beta -protein indicates cleavage should occur by a chymotrypsin-like enzyme.