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Amyloid aggregation of polypeptides is related to a growing number of pathologic states known as amyloid disorders. At present, it is clear that any proteins submitted to appropriate physicochemical environment can acquire fibrilar conformation. Fourier transform infrared spectroscopy (FTIR) has been a widely used technique to study temperature- induced amyloid-fibrils formation in vitro. In this way, strict changes and temperature controls are required to characterize the physicochemical basis of the amyloid-fibrils formation. In this article, the development of a highly efficient and accurate Peltier-based system to improve FTIR measurements is presented (see An Old Physics Phenomenon Applied to a Serious Biomedical Pathology. The accuracy of the thermostatic control was tested with biophysical parameters on biological samples probing its reproducibility. The design of the present device contributes to maintain the FTIR environment stable, which represents a real contribution to improve the spectral quality and thus, the reliability of the results.

Lewy bodies and Lewy neurites, neuropathological hallmarks of several neurological diseases, are mainly made of filamentous assemblies of α-synuclein. However, other macromolecules including Tau, ubiquitin, glyceraldehyde-3-phosphate dehydrogenase, and glycosaminoglycans are routinely found associated with these amyloid deposits. Glyceraldehyde-3-phosphate dehydrogenase is a glycolytic enzyme that can form fibrillar aggregates in the presence of acidic membranes, but its role in Parkinson disease is still unknown. In this work, the ability of heparin to trigger the amyloid aggregation of this protein at physiological conditions of pH and temperature is demonstrated by infrared and fluorescence spectroscopy, dynamic light scattering, small angle x-ray scattering, circular dichroism, and fluorescence microscopy. Aggregation proceeds through the formation of short rod-like oligomers, which elongates in one dimension. Heparan sulfate was also capable of inducing glyceraldehyde-3-phosphate dehydrogenase aggregation, but chondroitin sulfates A, B, and C together with dextran sulfate had a negligible effect. Aided with molecular docking simulations, a putative binding site on the protein is proposed providing a rational explanation for the structural specificity of heparin and heparan sulfate. Finally, it is demonstrated that in vitro the early oligomers present in the glyceraldehyde-3-phosphate dehydrogenase fibrillation pathway promote α-synuclein aggregation. Taking into account the toxicity of α-synuclein prefibrillar species, the heparin-induced glyceraldehyde-3-phosphate dehydrogenase early oligomers might come in useful as a novel therapeutic strategy in Parkinson disease and other synucleinopathies.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme related with Huntington's, Parkinson's and Alzheimer's diseases. The ability of negatively charged membranes to induce a rapid formation of GAPDH amyloid fibrils has been demonstrated, but the mechanisms by which GAPDH reaches the fibrillar state remains unclear. In this report, we describe the structural changes undergone by GAPDH at physiological pH and temperature conditions right from its interaction with acidic membranes until the amyloid fibril is formed. According to our results, the GAPDH-membrane binding induces a beta-structuring process along with a loss of quaternary structure in the enzyme. In this way, experimental evidences on the initial steps of GAPDH amyloid fibrils formation pathway are provided., (2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)

Inhibition or reversion of protein self-aggregation has been suggested as a possible preventive mechanism against amyloid diseases, and many efforts are underway to found out molecules capable to restrain the protein aggregation process. In this paper, the inhibitory effects of thyroid hormone analogues on heat-induced fibrillation process of serum albumin are reported. Among the analogues tested, 3,5,3′,5′-tetraiodothyroacetic and 3,5,3′-triiodothyroacetic acid showed the most important inhibitory effects on amyloid formation. Thyroxine exhibits a lesser protective effect, while 3,5,3′-triiodothyronine showed no significant inhibition. The gaining of a negative charge together with a size reduction of the hormone molecule could play an essential role in the inhibition of fibrils formation. According to infrared spectroscopy results, the thyroid hormones analogues protective effects proceed via the stabilization of the protein native structure. The current work demonstrates the effectiveness of naturally occurring molecules in the inhibition of albumin fibril formation. [ABSTRACT FROM AUTHOR]