Specific binding of a beta cyclodextrin dimer to the amyloid beta peptide modulates the peptide aggregation process
2012 (English)In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 51, no 21, 4280-4289 p.Article in journal (Refereed) Published
Alzheimer's disease involves progressive neuronal loss. Linked to the disease is the amyloid beta (A beta) peptide, a 38-43-amino acid peptide found in extracellular amyloid plaques in the brain. Cyclodextrins are nontoxic, cone-shaped oligosaccharides with a hydrophilic exterior and a hydrophobic cavity making them suitable hosts for aromatic guest molecules in water. beta-Cyclodextrin consists of seven alpha-D-glucopyranoside units and has been shown to reduce the level of fibrillation and neurotoxicity of A beta. We have studied the interaction between A beta and a beta-cyclodextrin dimer, consisting of two beta-cyclodextrin monomers connected by a flexible linker. The beta-cyclodextrin monomer has been found to interact with A beta(1-40) at sites Y10, F19, and/or F20 with a dissociation constant (K-D) of 3.9 +/- 2.0 mM. Here H-1-N-15 and H-1-C-13 heteronuclear single-quantum correlation nuclear magnetic resonance (NMR) spectra show that in addition, the beta-cyclodextrin monomer and dimer bind to the histidines. NMR translational diffusion experiments reveal the increased affinity of the beta-cyclodextrin dimer (apparent K-D of 1.1 +/- .5 mM) for A beta(1-40) compared to that of the beta-cyclodextrin monomer. Kinetic aggregation experiments based on thioflavin T fluorescence indicate that the dimer at 0.05-5 mM decreases the lag time of A beta aggregation, while a concentration of 10 mM increases the lag time. The beta-cyclodextrin monomer at a high concentration decreases the lag time of the aggregation. We conclude that cyclodextrin monomers and dimers have specific, modulating effects on the A beta(1-40) aggregation process. Transmission electron microscopy shows that the regular fibrillar aggregates formed by A beta(1-40) alone are replaced by a major fraction of amorphous aggregates in the presence of the beta-cyclodextrin dimer.
Place, publisher, year, edition, pages
2012. Vol. 51, no 21, 4280-4289 p.
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:su:diva-79766DOI: 10.1021/bi300341jISI: 000304492500006OAI: oai:DiVA.org:su-79766DiVA: diva2:551933