title: Analysis of the length distribution of amyloid fibrils by centrifugal sedimentation.
abstract: The aggregation of normally soluble peptides and proteins into amyloid fibrils is a process associated with a wide range of pathological conditions, including Alzheimer's and Parkinson's diseases. It has become apparent that aggregates of different sizes possess markedly different biological effects, with aggregates of lower relative molecular weight being associated with stronger neurotoxicity. Yet, although many approaches exist to measure the total mass concentration of aggregates, the ability to probe the length distribution of growing aggregates in solution has remained more elusive. In this work, we applied a differential centrifugation technique to measure the sedimentation coefficients of amyloid fibrils produced during the aggregation process of the amyloid β (M1-42) peptide (Aβ42). The centrifugal method has the advantage of providing structural information on the fibril distribution directly in solution and affording a short analysis time with respect to alternative imaging and analytical centrifugation approaches. We show that under quiescent conditions interactions between Aβ42 fibrils lead to lateral association and to the formation of entangled clusters. By contrast, aggregation under shaking generates a population of filaments characterized by shorter lengths. The results, which have been validated by cryogenic transmission electron microscopy (cryo-TEM) analysis, highlight the important role that fibril-fibril assembly can play in the deposition of aggregation-prone peptides.
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
authors.forename: Paolo
authors.initials: P
authors.lastname: Arosio
authors.affiliation: Department of Biochemistry and Structural Biology, Lund University, SE-221 00 Lund, Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Cedervall
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK. Electronic address: tpjk2@cam.ac.uk.
authors.forename: Tuomas P J
authors.initials: TP
authors.lastname: Knowles
authors.affiliation: Department of Biochemistry and Structural Biology, Lund University, SE-221 00 Lund, Sweden. Electronic address: sara.linse@biochemistry.lu.se.
authors.forename: Sara
authors.initials: S
authors.lastname: Linse
mesh_terms: D000682:Amyloid / Q000032:analysis* / Q000737:chemistry*; D002498:Centrifugation; D007700:Kinetics; D046529:Microscopy, Electron, Transmission
chemical_list: D000682:Amyloid
keywords: Amyloid; Aβ peptide; Differential centrifugation; Length distribution; Polydispersity; Size distribution