Prostatic corpora amylacea.

Alpha-synuclein (alpha-Syn) has been identified as a component of intracellular fibrillar deposits in Parkinson's disease. Though the real pathogenesis is still unknown, many investigations have revealed that conformational alteration and fibril formation of alpha-Syn protein have an important role in causing the disease. In this work, we introduced the g-factor spectra of solid-state circular dichroism to estimate the secondary structure contents of alpha-Syn fragments in amyloids. Fourier-transform infrared (FTIR) was also applied to confirm the structural formation. The results suggest that the central hydrophobic region is critical for beta-sheet formation and the conformational alteration is the foundation of protein abnormal aggregation. The research provides a practical approach to estimate the secondary structure contents of protein amyloids and further insight into the relevance of structural transformation and amyloidogenesis.

Amyloid↗

PubMed2006

The organization of aromatic side groups in an amyloid fibril probed by solid-state 2H and 19F NMR spectroscopy.

Some 25 diseases are associated with proteins and peptides that assemble into amyloid fibrils composed of beta-strands connected by hydrogen bonds oriented parallel to the fiber long axis. There is mounting evidence that amyloid formation involves specific interactions between amino acid side groups, which bring together beta-sheets to form layers with buried and exposed faces. This work demonstrates how a combination of solid-state 2H and 19F NMR experiments can provide constraints on fibril architecture by probing the environment and spatial organisation of aromatic side groups. It is shown that phenylalanine rings within fibrils formed by a decapeptide fragment of the islet amyloid polypeptide, amylin, are highly motionally restrained and are situated within 6.5 A of one another. Taken together with existing structural constraints for this peptide, these results are consistent with a fibril architecture that comprises layers of two or more beta-sheets, with the aromatic residues facing into the inter-sheet space and possibly engaged in pi-pi interactions. The methods presented will be of general utility in exploring the architecture of fibrils of larger, full-length peptides and proteins, including amylin itself.

Amyloid↗

PubMed2006

Classification of amyloidosis: misdiagnosing by way of incomplete immunohistochemistry and how to prevent it.

Classification of every individual case of amyloid disease is necessary in order to recognize its origin and its possible pathogenesis for therapeutic consideration. Classification of the amyloids can be performed in different ways. One method primarily exploits serum proteins-but these are risk factors only, and therefore render only ancillary information. In principle, one cannot establish the diagnosis alone through their use. Another approach analyzes the origin of the deposited amyloids, either by extracting the amyloid proteins followed by immunochemical or chemical analysis, or by using immunohistochemistry. Based on chemical analysis of prototypes of amyloid fibril proteins, we have developed a profile of antibodies over the years that specifically identify amyloid in tissue sections. These antibodies have been used for years as a routine service for clinicians and pathologists in immunohistochemically classifying amyloid found in formalin-fixed tissue sections. The typing is always controlled by established amyloid classes. In several cases, we have been asked for a second opinion on a diagnosed amyloid class. Our own immunohistochemical data were then compared with those submitted. These submitted immunohistochemical results represented misdiagnoses of amyloid classes in most patients, since the technique performed was usually incomplete. It is the purpose of this report to analyze such cases and to document some of the typical mistakes. Here, we show how to avoid common pitfalls and how one can arrive at a correct diagnosis using immunohistochemistry appropriately.

Amyloid↗