title: Self-assembly of ovalbumin into amyloid and non-amyloid fibrils.
abstract: We study the fibrillation pathway of ovalbumin protein and report the simultaneous formation of several types of fibrils, with clear structural and physical differences. We compare the fibrillation mechanisms at low pH with and without salt, and follow the kinetics of fibrils growth by atomic force microscopy (AFM), static and dynamic light scattering (SLS, DLS), and small-angle X-ray scattering (SAXS). We show that, among the morphologies identified, long semiflexible amyloid fibrils (type I), with persistence length Lp∼3 μm, Young's modulus E∼2.8 GPa, and cross-β structure are formed. We also observe much more flexible fibrils (type III, Lp∼63 nm), that can assemble into multistranded ribbons with time. They show significantly lower intrinsic stiffness (1.1 GPa) and a secondary structure, which is not characteristic of the well-ordered amyloids, as determined by circular dichroism (CD), wide-angle X-ray scattering (WAXS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). In between these two main classes of fibrils, a third family, with intermediate flexibility (type II, Lp∼300 nm), is also resolved.
authors.affiliation: Food and Soft Material Science, Institute of Food, Nutrition and Health, ETH Zürich, Schmelzbergstrasse 9, LFO E 23, 8092 Zürich, Switzerland.
authors.forename: Cecile
authors.initials: C
authors.lastname: Lara
authors.forename: Simon
authors.initials: S
authors.lastname: Gourdin-Bertin
authors.forename: Jozef
authors.initials: J
authors.lastname: Adamcik
authors.forename: Sreenath
authors.initials: S
authors.lastname: Bolisetty
authors.forename: Raffaele
authors.initials: R
authors.lastname: Mezzenga
mesh_terms: D000682:Amyloid / Q000138:chemical synthesis*; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D010047:Ovalbumin / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D014965:X-Rays
chemical_list: D000682:Amyloid; D010047:Ovalbumin