The formation of spherulites by amyloid fibrils of bovine insulin

M R H Krebs, C E MacPhee, A F Miller, L E Dunlop, C M Dobson, A M Donald, Cait MacPhee

Research output: Contribution to journalArticlepeer-review

Abstract

Bovine insulin has long been known to self-assemble in vitro into amyloid fibrils. We have observed a further higher-order self-association of the protein into spherical structures, with diameters typically around 50 mum but ranging from 10 to 150 mum. In a polarizing light microscope, these structures exhibit a "Maltese-cross" extinction pattern typical of spherulites. Spherical structures of a similar size distribution can be observed in the environmental scanning electron microscope, which also reveals the presence of significant amounts of water in the structures. The spherulites contain a large quantity of well defined amyloid fibrils, suggesting that they are formed at least in part as a consequence of the self-assembly of preformed fibrils. Similar structures also have been observed in the tissues of patients suffering from amyloid disorders. The ability of amyloid fibrils to form such higher-order assemblies supports the hypothesis that they represent a generic form of polypeptide structure with properties that are analogous to those of classical synthetic polymers.

Original languageEnglish
Pages (from-to)14420-14424
Number of pages5
JournalProceedings of the National Academy of Sciences
Volume101
Issue number40
DOIs
Publication statusPublished - 5 Oct 2004

Keywords

  • TRANSFORM INFRARED-SPECTROSCOPY
  • LIQUID-CRYSTAL SPHERULITES
  • CANINE MAMMARY-TUMORS
  • ELECTRON-MICROSCOPY
  • PROTEIN
  • CHITIN
  • PH
  • FIBRILLOGENESIS
  • POLYMERIZATION
  • NUCLEATION

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