Immobilized Amyloid Hexamer Fragments to Map Active Sites of Amyloid-Targeting Chemicals

As amyloid-beta (A beta) peptide is considered a biomarker and pathological culprit of Alzheimer's disease, A beta- targeting compounds have been investigated for diagnostics development and drug discovery of the disorder. Unlike amyloid plaque targeting agents, such as clinically available amyloid radiotracers intercalating into the beta-sheet structures of the aggregates, monomer and oligomer targeting chemicals are difficult to develop, as the transient and polymorphic nature of these peptides impedes their structural understanding. Here, we report a mapping approach to explore targeting residues of A beta-imaging probes and A beta-regulating drug candidates by utilizing a set of fragmented A beta hexamers immobilized on a 96-well microplate in combination with fluorescent full-length A beta for on-plate aggregation. To evaluate the mapping potential of the peptide plate, we tested previously reported fluorescent imaging agents (CRANAD-28, bis-ANS), aggregation inhibitors (curcumin, scyllo-inositol), and aggregate dissociators (necrostatin-1, sunitinib) targeting A beta. Our approach enabled mechanistic understanding of compounds targeting nonfibrillar A beta on an interacting sequence level.

Automated summary

This article introduces a method for identifying A beta peptide, which is gradually becoming a biomarker for Alzheimer's disease, and for targeting compounds used in diagnostics and drug development. By immobilizing fragmented A beta hexamers on a microplate and aggregating them with fluorescent full-length A beta, a mapping approach is reported for exploring targeting residues of A beta-imaging probes and A beta-regulating drug candidates. Through experimental validation, the authors were able to gain mechanistic understanding of how these compounds target nonfibrillar A beta.