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Revealing molecular-level surface structure of amyloid fibrils in liquid by means of frequency modulation atomic force microscopy.
journal contributionposted on 2023-06-07, 23:37 authored by Takeshi Fukuma, Anika S Mostaert, Louise SerpellLouise Serpell, Suzanne P Jarvis
We have investigated the surface structure of islet amyloid polypeptide (IAPP) fibrils and a-synuclein protofibrils in liquid by means of frequency modulation atomic force microscopy (FM-AFM). Ångström-resolution FM-AFM imaging of isolated macromolecules in liquid is demonstrated for the first time. Individual ß-strands aligned perpendicular to the fibril axis with a spacing of 0.5 nm are resolved in FM-AFM images, which confirms cross-ß structure of IAPP fibrils in real space. FM-AFM images also reveal the existence of 4 nm periodic domains along the axis of IAPP fibrils. Stripe features with 0.5 nm spacing are also found in images of a-synuclein protofibrils. However, in contrast to the case for IAPP fibrils, the stripes are oriented 30° from the axis, suggesting the possibility of ß-strand alignment in protofibrils different from that in mature fibrils or the regular arrangement of thioflavin T molecules present during the fibril preparation aligned at the surface of the protofibrils.
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- Biochemistry Publications
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