The aggregation of misfolded proteins into amyloid fibrils, and the importance of this step for various diseases, is well known. However, it is becoming apparent that the fibril is not the only structure that aggregating proteins of widely different types may adopt. Around the isoelectric point, when the net charge is essentially zero, rather monodisperse and quasi-amorphous nanoscale particles form. These particles are found to contain limited runs of β-sheet structure, but their overall organization is random. These nanoparticles have the potential to be useful for such applications as the slow release of drugs. The amyloid fibrils form away from the isoelectric point, but over certain ranges of, e.g., pH, the fibrils themselves do not exist freely, but form suprafibrillar aggregates termed spherulites. These consist of fibrils radiating from a central nucleus, and form by new species attaching to the ends of growing fibrils, rather than by the aggregation of pre-existing fibrils. Under the polarizing light microscope, they exhibit a Maltese cross shape due to their symmetry. The rate of aggregation is determined by factors involving (at least) protein size, concentration, presence of salt and charge. The occurrence of spherulites, which have been found in vivo as well as in vitro, appears to be generic, although the factors which determine the equilibrium between free fibril and spherulite are not as yet clear.
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Conference Article|
July 22 2009
Protein aggregation: more than just fibrils
Mark R.H. Krebs;
Mark R.H. Krebs
1
1Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
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Kristin R. Domike;
Kristin R. Domike
2
1Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
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Athene M. Donald
Athene M. Donald
3
1Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
3To whom correspondence should be addressed (email amd3@cam.ac.uk).
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Publisher: Portland Press Ltd
Received:
January 05 2009
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biochem Soc Trans (2009) 37 (4): 682–686.
Article history
Received:
January 05 2009
Citation
Mark R.H. Krebs, Kristin R. Domike, Athene M. Donald; Protein aggregation: more than just fibrils. Biochem Soc Trans 1 August 2009; 37 (4): 682–686. doi: https://doi.org/10.1042/BST0370682
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