Synthesis & structural studies on amyloid fibrils & oligomers of Alzheimer's A-beta & model Poly-Q
Molecular self-organization and self-assembly are processes by which Nature builds complex three-dimensional multicomponent structures with well-defined functions starting from simple building blocks such as oligonucleotides, lipids or peptides. In the case of polypeptides, these phenomena have been the focus of intense research in recent years, after the realization that self-assembly is at the basis of the formation of oligomers and of insoluble amyloid fibrils.
These involve the most diffused neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease, Creutzfeld-Jakobs Syndrome, type II diabetes and others. The ability to form ordered amyloid aggregates was shown also for a large number of non-pathogenic polypeptides under suitable solvent, temperature and pH conditions. These observations provided a unique opportunity for the rational development of ordered supramolecular structures for biotechnology. Considering the key role that the peptide self-assembly process holds for vast scientific, biomedical and technological communities, it is of interest to characterize not only the structural properties of the final structures, but most importantly the early steps of oligomer formation at the atomic level. From the biomedical side, there is mounting evidence suggesting that the toxicity of the fatal neurodegenerative diseases may be caused by the intermediate oligomers in addition to the mature fibrils. On the biotechnological side, the study of aggregation mechanisms may be the source of inspiration for the development of ordered, rationally designed nanostructures with potentially interesting applications from material sciences to tissue engineering, from molecular electronics to drug delivery.
Previous studies demonstrated the tendency of polyGln sequences to form insoluble aggregates. It was shown that a chemically synthesized Q15 peptide, under certain conditions, aggressively aggregates to form β-sheet-rich structures appearing as short filaments in electron micrographs. Proteins containing longer polyGln peptides, generated by recombinant expression, aggregate in a polyGln repeat length-dependent manner to form amyloid, or amyloid-like, fibrils. On this basis, it might be justified to include the expanded polyglutamine diseases into the growing family of amyloid diseases known to affect either the brain or organs in the periphery. Amyloid fibrils exhibit a number of defining characteristics, and there is no general agreement on what the minimum criteria should be for classifying an aggregate as amyloid nor on how to classify aggregates that meet some criteria but fail others. With the recent development of protocols for solubilizing chemically synthesized polyGln peptides of repeat lengths up to at least Q50, it has become possible to conduct controlled studies of the aggregation process and to characterize the structures of both monomeric peptides and aggregates.
Goal
(i) To synthesize new peptides, which are models of aggregating peptides responsible for diseases of Alzheimer (A/beta peptides) and Huntington (Poly/Q peptides), purification and characterization of these peptides.
(ii) Analysis of aggregation properties of these polypeptides in bulk and on a solid support by NMR and AFM-microscopy; Elucidation of the aggregation mechanism.
(iii) Analysis of interaction of these polypeptides with model lipid biomembranes with a variety of techniques, including 31P NMR, IR-spectroscopy, NMR diffusometry, 13C and 15N CP/MAS NMR spectroscopy.
Contact
Oleg Antzutkin
- Professor and Head of Subject
- 0920-492524
- oleg.antzutkin@ltu.se
- Oleg Antzutkin
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