Two-dimensional infrared spectroscopy reveals the complex behaviour of an amyloid fibril inhibitor
Author: ["Chris T. Middleton","Peter Marek","Ping Cao","Chi-cheng Chiu","Sadanand Singh","Ann Marie Woys","Juan J. de Pablo","Daniel P. Raleigh","Martin T. Zanni"]
Publication: Nature Chemistry
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Abstract
Amyloid formation has been implicated in the pathology of over 20 human diseases, but the rational design of amyloid inhibitors is hampered by a lack of structural information about amyloid–inhibitor complexes. We use isotope labelling and two-dimensional infrared spectroscopy to obtain a residue-specific structure for the complex of human amylin (the peptide responsible for islet amyloid formation in type 2 diabetes) with a known inhibitor (rat amylin). Based on its sequence, rat amylin should block formation of the C-terminal β-sheet, but at 8 h after mixing, rat amylin blocks the N-terminal β-sheet instead. At 24 h after mixing, rat amylin blocks neither β-sheet and forms its own β-sheet, most probably on the outside of the human fibrils. This is striking, because rat amylin is natively disordered and not previously known to form amyloid β-sheets. The results show that even seemingly intuitive inhibitors may function by unforeseen and complex structural processes. Molecular inhibitors of amyloid formation could help combat Alzheimer's disease, type 2 diabetes, and other major human diseases. Here, two-dimensional infrared spectroscopy and residue-specific isotope labelling are used to obtain detailed structural information on amyloid-inhibitor complexes. The unexpected behaviour observed helps to explain the moderate activity of the inhibitor studied.
Cite this article
Middleton, C., Marek, P., Cao, P. et al. Two-dimensional infrared spectroscopy reveals the complex behaviour of an amyloid fibril inhibitor. Nature Chem 4, 355–360 (2012). https://doi.org/10.1038/nchem.1293