Functional Amyloid

Abstract

Amyloid is notorious for its association with a range of debilitating and incurable human diseases. However, evidence is now emerging that the amyloid fold may be functional and utilized by a broad range of organisms. Atomic force microscopy has helped in the identification of amyloid in the natural adhesives of biofouling terrestrial algae that attach to a range of natural and man-made surfaces. AFM is now being used to pull apart a variety of amyloid fibrils in order to elucidate their structure.is because in their misfolded state they can readily aggregate into highly ordered amyloid fibrils. These fibrils are stable and insoluble, usually consisting of multiple levels of structure of which intermo- What Is Amyloid?Over the last decade it has become evident that misfolded proteins are of huge biological and medical importance. This l. to. r.: Prof. Suzanne P. Jarvis and Dr. Anika S. Mostaert Keywords:Nonpathogenic amyloid, physiological amyloid, force-extension curve, mechanical function, atomic force microscopy lecular β-sheets are a generic component. These sheets are the building blocks of protofilaments that can be several nanometres in diameter, and themselves make up the mature fibrils like strands of a rope. A variety of interactions have been implicated in amyloid structures, including strong hydrophobic interactions within the core of the fibril and interior salt-bridges. Amyloid, amyloid-like fibrils (the latter being defined S c a n n i n g S e c t i o n as "model" amyloid fibrils formed in vitro) and their precursor oligomers have been studied extensively due to the apparently central role of amyloid formation in diseases such as Alzheimer's, Parkinson's, type II diabetes and Creutzfield-Jacob disease. Recently, the possible role of amyloid aggregation in a far broader range of degenerative diseases has been highlighted, and it has been suggested that amyloidosis could be a universal disease of aging [1]. Indeed, there is increasing experimental evidence that the amyloid state is a generic protein fold [2] not dependent on amino acid sequence, but often depends on environmental conditions. It could thus be inferred that given sufficient time any proteinaceous part of any organism may suffer the consequences of pathogenic amyloid formation. It is therefore particularly important to understand what triggers and controls amyloid formation, the mechanism of toxicity and how this may be prevented. Nonpathogenic AmyloidSurprisingly, physiological amyloid has been found in a diverse range of organisms from bacteria [3] to mammals [4] in recent years. Due to the very repetitive nature of the amyloid quarternary structure, we have been able to apply AFM to pinpoint natural materials where the amyloid structure may occur. Pulling apart any repetitive structure is readily apparent in the force-extension curves produced when an AFM tip binds (usually non-specifically) to the sample surface, and the substrate and tip are moved gradually apart, thus unravelling the structure until it either breaks or detaches fr...

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“…4,[6][7][8][9][10][11][12][13][14] The chemical analysis of the inorganic solids mentioned above by ICP OES using conventional acid dissolution methods, in open flasks on hot plate, 15 usually involves costly and time-consuming procedures for sample preparation, 3 requiring a long analysis time and large amounts of reagents. Additionally, such conventional procedures do not assure complete dissolution of some solid inorganic samples, especially geological samples 15,16 (including silicates 8,13,17 and aluminosilicates) 14,16 even when a large amount of concentrated acids is used. 3,8 Moreover, these procedures allow analytes loses and samples contamination, 4 with the accuracy, reproducibility, and precision being affected.…”

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