Diffraction to study protein and peptide assemblies

Intrinsically Disordered Enamel Matrix Protein Ameloblastin Forms Ribbon-like Supramolecular Structures via an N-terminal Segment Encoded by Exon 5

“…Surprisingly, the thickness of the ribbons was determined by AFM to be much lower than previously found for other self-assembled fibrous IDPs (52). The determined thickness of AMBN ribbons was comparable to the thickness of ␤-sheet structures or to that reported for ssDNA (53)(54)(55).…”

A thermodynamic analysis of fibrillar polymorphism

“…Binding of ions may also lead to the salt fibrils' unique fiber diffraction peaks where the characteristic band around 10-11 Å from inter-sheet packing is missing. It has been suggested that bound inorganic ions could reduce the ability to form inter-sheet packing or lead to a mixture of both parallel and antiparallel sheets which will strongly attenuate the 10-11 Å band [40,41]. In contrast to NaCl, even low millimolar concentrations of Na 2 SO 4 stabilize the glucagon fibrils [14].…”

“…Folding of proteins to their native state is generally driven by hydrophobic interactions, where the non-polar side groups tend to be buried in the interior of the protein while the polar side groups will tend to remain exposed. In Biophysical Chemistry 149 (2010) [40][41][42][43][44][45][46] contrast, fibril formation is driven by strong backbone interactions which may lead to the unfavorable burial of polar and charged groups, leading to a decrease in the ΔC p [12,13]. Due to the complexity and the many steps involved in the fibrillation mechanism, fibril formation may be under kinetic control, so that the end structure is not necessarily the one with the lowest possible energy [14].…”

Defective Protein Folding and Aggregation as the Basis of Neurodegenerative Diseases: The Darker Aspect of Proteins

“…They have a tensile strength similar to that of steel [40]. Amyloid fibrils are insoluble and heterogeneous and they are mostly studied using techniques involving X-ray fiber diffraction, electron microscopy [41], and more recently solid state nuclear magnetic resonance [42] and electroparamagnetic resonance [43]. Electron and atomic force microscopy have provided a deeper insight into the macromolecular structure of amyloid fibrils and have shown that fibrils are long, straight and unbranching, and are made up of individual subunits named ''protoflaments'' [44][45][46].…”