Modeling of Biomolecular Systems Interactions, Dynamics, and Allostery: Bridging Experiments and Computations - September 10-14, 2014, Istanbul, Turkey

Modeling of Biomolecular Systems Interactions, Dynamics, and Allostery Poster Session II

64-POS Board 17 Assembly of the Alzheimer's Disease Associated Amyloid beta Peptide during the Lag Phase of Fibril Formation Luitgard Nagel-Steger 1,2 , Oleksandr Brener 1,2 , Martin Wolff 1,2 , Dmitry Unuchek 4 , Bo Zhang 1,3 , Dieter Willbold 1,2 . 1 RC-Juelich, Juelich, Germany, 2 Heinrich-Heine-University, Duesseldorf, Germany, 3 RC- Juelich, Juelich, Germany, 4 Moscow Institute of Physics and Technology, Dolgoprudniy, Russian Federation. One of the most important targets in Alzheimer’s therapy is still the proteolytic fragment of the amyloid precursor protein, called amyloid beta peptide. This fragment is between 39 and 43 amino acids long and is marked by its high tendency to self-associate. The self-assembly, which finally leads to the formation of amyloid fibrils, has to proceed via an unknown number of intermediate structures, among which a more potent therapeutic target than the fibril is suspected. Additionally other pathways might exist, leading also to the formation of small oligomeric species, which might as well as the on-pathway species be responsible for the toxic effects the Abeta peptide exerts on neuronal cells. OBJECTIVE: Identification and characterization of early, distinct assemblies of the amyloid beta peptide in solution regarding size, shape and fraction. METHODS: Sedimentation velocity centrifugation, complemented by density gradient centrifugation, atomic force microscopy, fluorescence assays and CD-spectroscopy were utilized. RESULTS: Aside from the monomeric peptide a set of globular assemblies have been identified in solutions which were still in the lag phase of amyloid formation. These species had increased beta sheet content, were negative for thioflavin T staining and exhibited a stronger cytotoxicity than amyloid fibrils at the same mg/ml concentrations. CONCLUSIONS: By sedimentation velocity centrifugation size-, shape information and fraction of distinct oligomeric species of the amyloid beta peptide could be retrieved simultaneously from the same sample solution.

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