Alzheimer's β‐amyloid peptide specifically interacts with and is degraded by insulin degrading enzyme

Abstract
Cerebral deposition of β-amyloid peptide (βA) is a hallmark of Alzheimer's disease. Concentration of βA could play a critical role in the rate of amyloid deposition. It is therefore of considerable importance to identify proteases involved in processing of βA. 125I-labeled synthetic βA specifically cross-linked to a single protein with M r = 110,000 in cytosol fractions from rat brain and liver. This protein was identified as insulin degrading enzyme (IDE) since the labeling of the 110 kDa protein was completely blocked by an excess of insulin, and anti-IDE monoclonal antibodies precipitated the labeled protein. Purified rat IDE effectively degraded βA.