Formation of β-amyloid plaques in Alzheimer's disease is initiated by intermolecular contact of the 5-amino acid sequence, KLVFF, in β-amyloid peptides ranging in size from 40 to 43 residues. Through optimization of binding avidity using structure/function studies, we have found that the retro-inverso peptide, ffvlk, binds artificial fibrils made from Aβ1-40 with moderate affinity (Kd = 5 × 10-10 M). Conjugates having two copies of this peptide, whether connected by a long poly(ethylene glycol) (PEG) spacer or just two amino acids, display about 100-fold greater affinity for fibrils. Placing six copies of ffvlk on a branched PEG resulted in a 10 000-fold greater affinity (Kd = 1 × 10-10 M) than the monomer peptide. This increased affinity was accompanied by more effective inhibition of the thioflavin T fluorescence signal, which correlates with neurotoxicity of plaques and fibrils. We propose that conjugates bearing several copies of ffvlk may be useful as diagnostic and therapeutic agents for Alzheimer's disease.
ASJC Scopus subject areas
- Organic Chemistry
- Clinical Biochemistry
- Biochemistry, Genetics and Molecular Biology(all)