Interplay between Copper, Neprilysin, and N-Truncation of β-Amyloid

Abstract

Sporadic Alzheimer's disease (AD) is associated with an inefficient clearance of the β-amyloid (Aβ) peptide from the central nervous system. The protein levels and activity of the Zn2+-dependent endopeptidase neprilysin (NEP) inversely correlate with brain Aβ levels during aging and in AD. The present study considered the ability of Cu2+ ions to inhibit human recombinant NEP and the role for NEP in generating N-truncated Aβ fragments with high-affinity Cu2+ binding motifs that can prevent this inhibition. Divalent copper noncompetitively inhibited NEP (Ki = 1.0 μM), while proteolysis of Aβ yielded the soluble, Aβ4-9 fragment that can bind Cu2+ with femtomolar affinity at pH 7.4. This provide..