Amyloids: Not Only Pathological Agents but Also Ordered Nanomaterials

Abstract

Amyloid fibers constitute one of the most abundant and important naturally occurring self-associated assemblies. A variety of protein and peptide molecules with various amino acid sequences form these highly stable and well-organized assemblies under diverse conditions. These assemblies display phase states ranging from liquid crystals to rigid nanotubes. The potential applications of these supramolecular assemblies exceed those of synthetic polymers since the building blocks may introduce biological function in addition to mechanical properties. Here we review the structural characteristics of amyloidal supramolecular assemblies, their potential use as either natural or de novo designed sequences, and the range of applications that have been demonstrated so far.

Kinetic theory of amyloid fibril templating

“…While these additional alignments are fully consistent with the β-sheet structure of the fibril, presumably they are higher in free energy due to sub-optimal sidechain packing interactions. These interactions increase the free energy per peptide group to 1 . Within this simple model, the partition function describing the various alignments for a single molecule within the fibril is…”

“…This lifetime is a function of , the strength of the bonds holding the molecule onto the fibril end. A requirement for successful templating is that t bond ( 0 ) > t bond ( 1 ). Section II B is devoted to calculating the residence time t bond to determine how it depends on the binding affinity.…”

“…This is to be distinguished from the "steric templating" mechanism to be discussed shortly that involves a three-body interaction. In direct templating the binding affinity between two molecules in the optimal alignment is described by 0 , while the binding affinity between any other set of sidechain pairings is 1 .…”

Implantable amyloid hydrogels for promoting stem cell differentiation to neurons

“…These properties of amyloids make them attractive for designing various functional materials for nanotechnological/biotechnological applications. [4][5][6][7][8] Moreover, the combination of hydrophobicity and charged residues (depending on the sequence) makes the surface of amyloid fibrils unique and enables them to bind to not only large macromolecules/polymers but also small molecules and cells. [9][10][11] Cell transplantation holds great therapeutic potential for the regeneration of the central nervous system, but poor cell survival upon transplantation remains a significant problem.…”

Non-equilibrium nature of two-dimensional isotropic and nematic coexistence in amyloid fibrils at liquid interfaces

“…The efforts made to understand the microstructure of anisotropic particle-laden interfaces demonstrate high fundamental interest. In the case of amyloid fibrils, in particular, three main areas of research are noteworthy 21 . First and foremost, their accumulation at biological interfaces is a crucial step in pathological processes such as plaque/deposit formation 22 in membrane-associated amyloid diseases such as Alzheimer's or type II diabetes mellitus 23 .…”