title: Biophysical insight reveals tannic acid as amyloid inducer and conformation transformer from amorphous to amyloid aggregates in Concanavalin A (ConA).
abstract: The aggregation phenomenon (amyloid and amorphous) is associated with several pathological complications in human, such as Alzheimer's, Parkinson's, Huntington, Cataract diseases, and Diabetes mellitus type 2. In the present study we are offering evidence and breaking the general belief with regard to the polyphenols action as protein aggregate inhibitors. Herein we confirm that tannic acid (TA) is not only an amyloid inducer, but also it switches one type of conformation, ultimately morphology, into another. We ascertain based on our findings that aggregates are not rigid structures and the stability can be challenged under certain conditions. This study also confirms that unfolded and amorphous aggregates can serve as precursors of amyloids and TA interactions with unordered aggregates (amorphous) bringing orderliness in the conformation via amyloidosis. The shifting of unordered conformation toward orderliness is governed by the modulation in surface hydrophobic patches in Concanavalin A (ConA). Hence, a degree of exposed hydrophobic cluster can be claimed as a strong parameter to detect and distinguish the native, amorphous and both types of amyloids. Turbidity and Rayleigh light scattering measurements followed similar pattern while Thioflavin T and 1-anilino-8-naphthalene sulfonate fluorescence assays of the binding with amorphous and amyloid followed an inverse relation. Electron microscopic studies revealed the morphological variation in the ConA at 65°C as amorphous while the ConA treated with TA followed by heat treatment at 65°C was defined as amyloid in nature. Interestingly for the first time we are reporting the slight agglutination activity by the ConA amyloids.
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Mohsin Vahid
authors.initials: MV
authors.lastname: Khan
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Mohd
authors.initials: M
authors.lastname: Ishtikhar
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Mohammad Khursheed
authors.initials: MK
authors.lastname: Siddiqui
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Masihuz
authors.initials: M
authors.lastname: Zaman
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Tajalli Ilm
authors.initials: TI
authors.lastname: Chandel
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Nabeela
authors.initials: N
authors.lastname: Majid
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Mohd Rehan
authors.initials: MR
authors.lastname: Ajmal
authors.affiliation: b Department of Pharmaceutical Chemistry , College of Pharmacy, King Saud University , P.O. Box 2457, Riyadh 11451 , Saudi Arabia.
authors.forename: Ali Saber
authors.initials: AS
authors.lastname: Abdelhameed
authors.affiliation: c Molecular Biology Department, Genetic Engineering and Biotechnology Division , National Research Centre , Dokki, Cairo , Egypt.
authors.forename: Yasser E
authors.initials: YE
authors.lastname: Shahein
authors.affiliation: a Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh 202002 , India.
authors.forename: Rizwan Hasan
authors.identifier: http://orcid.org/0000-0002-9965-8982
authors.initials: RH
authors.lastname: Khan
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D052160:Benzothiazoles / Q000737:chemistry; D055592:Biophysical Phenomena; D003208:Concanavalin A / Q000737:chemistry*; D066329:Protein Aggregates / Q000187:drug effects; D011487:Protein Conformation; D013057:Spectrum Analysis; D013634:Tannins / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000682:Amyloid; D052160:Benzothiazoles; D066329:Protein Aggregates; D013634:Tannins; D003208:Concanavalin A; C009462:thioflavin T
keywords: ConA; amorphous; amyloid; inducer; tannic acid