Synthesis & structural studies on amyloid fibrils & oligomers of Alzheimer's A-beta peptides

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.

Goal

(i) Synthesis of new peptides, which are models of aggregating peptides responsible for diseases of Alzheimer (A-beta peptides), purification and characterization of these peptides.

(ii) Analysis of aggregation properties of these polypeptides in bulk and on a solid support by NMR. 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.

References

[1] C. Lendel, M. Bjerring, A. Dubnovitsky, R.T. Kelly, A. Filippov, O.N. Antzutkin, N.C. Nielsen, T. Härd A hexameric peptide barrel as building block of amyloid b protofibrils. // Angewandte Chemie International Edition 2014. V.53. P.12756-12760.

[2] K.S. Usachev, A.V. Filippov, O.N. Antzutkin, V.V. Klochkov The Arctic mutation of Alzheimer’s Aβ peptide in an SDS micelle. // Journal of Molecular Structure. 2014. V.1076. P.518-523.

[3] O. N. Antzutkin, D. Iuga, A. Filippov, J. Becker-Baldus, S. P. Brown, R. Dupree Hydrogen bonding in Alzheimer´s amyloid fibrils probed by 15N(17O)REAPDOR NMR. // Angewandte Chemie International Edition. 2012. V.51. P.10289-10292.

[4] N. Norlin, M. Hellberg, A. Filippov, A. A. Sousa, G. Grobner, R. D. Leapman, N. Almquist, O. N. Antzutkin Aggregation and fibril morphology of the arctic mutation of Alzheimers Abeta peptide by CD, TEM, STEM and in situ AFM. // J. Structural Biol. 2012. V.178. P.174-189.