Critical aggregation concentration for the formation of early Amyloid-? (1-42) oligomers.

ABSTRACT: The oligomers formed during the early steps of amyloid aggregation are thought to be responsible for the neurotoxic damage associated with Alzheimer's disease. It is therefore of great interest to characterize this early aggregation process and the aggregates formed, especially for the most significant peptide in amyloid fibrils, Amyloid-?(1-42) (A?42). For this purpose, we directly monitored the changes in size and concentration of initially monomeric A?42 samples, using Fluorescence Correlation Spectroscopy. We found that A?42 undergoes aggregation only when the amount of amyloid monomers exceeds the critical aggregation concentration (cac) of about 90?nM. This spontaneous, cooperative process resembles surfactants self-assembly and yields stable micelle-like oligomers whose size (?50 monomers, R h ? 7-11?nm) and elongated shape are independent of incubation time and peptide concentration. These findings reveal essential features of in vitro amyloid aggregation, which may illuminate the complex in vivo process.

SUBMITTER: Novo M 

PROVIDER: S-EPMC5789034 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature