Simultaneous Detection of Tyrosine and Structure-Specific Intrinsic Fluorescence in the Fibrillation of Alzheimer's Associated Peptides |
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Authors: | Anurag Singh Suparna Khatun Dr. Amar Nath Gupta |
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Affiliation: | Biophysics and Soft Matter Laboratory Department of Physics, Indian Institute of Technology, Kharagpur, 721302 India |
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Abstract: | Understanding of the structural changes during their aggregation and interaction is a prerequisite for establishing the precise clinical relevance of human islet amyloid polypeptide (hIAPP) (involved in Type-II Diabetes Mellitus) in the treatment of Alzheimer's disease stemmed from beta-amyloid (Aβ). Herein, we show that the steady-state emission spectra obtained from photoluminescence (PL) simultaneously capture both the tyrosine derivative (tyrosinate) and the structure-specific intrinsic fluorescence during the aggregation of Aβ and hIAPP. We observe multiple peaks in the emission spectra which exist for structure-specific intrinsic fluorescence, and use the second derivative UV-Vis spectra and the shift in the tyrosine peak as a quantitative measure of the dissimilitude in the electronic states and the fibril growth. We further applied these techniques to detect the static electric field (0, 40, 120, 200 V/cm) induced promotion and inhibition of fibrillation in Aβ, hIAPP and their electric field dependent role in the fibrillation of Aβ : hIAPP(1 : 1). The results were corroborated by field-emission scanning electron microscopy (FESEM), and the determinations of secondary structures by Fourier transform infrared spectroscopy (FTIR). The results indicate that the emission spectrum can be used as a sensor to detect the presence of fibrils; hence for screening potential inhibitors of amyloid fibrillation. |
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Keywords: | Alzheimer's disease amyloidbeta and hIAPP photoluminescence protein-protein interactions static electric field |
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