Biophysical Society Thematic Meeting - October 25-30, 2015

Polymers and Self Assembly: From Biology to Nanomaterials

Tuesday Speaker Abstracts

Solid-State NMR Structural Characterization of Peptide Assemblies: Oligomeric Aβ(1-42) and Designer Peptide Nanofibers Anant K. Paravastu . Georgia Institute of Technology, Atlanta, USA. Our group has focused on probing structures of self-assembled peptides using solid-state NMR spectroscopy. For the 42-residue Alzheimer’s amyloid-β peptide (Aβ(1-42)), emerging understanding of environment-dependent assembly pathways has made it possible to produce oligomeric samples with a stable homogeneous molecular structure. We seek to understand how oligomeric structures are distinct from fibrillar structures in order to provide a structural basis for differing neuronal toxicity profiles. We are also interested in designer peptides with amino acid sequences that were rationally designed to promote specific self-assembled molecular structures. We will show how the combination of solid-state NMR and constrained molecular dynamics computer simulations could provide the specific structural information necessary to test proposed structural models from the literature. For 150 kDa Aβ(1-42) oligomers, we will show data in support of an antiparallel β-sheet structure that is distinct from the in-register parallel motif commonly observed for amyloid fibrils. We will present a structural model for RADA16-I designer nanofibers that is composed of parallel β-sheets, unlike the antiparallel β-sheet structure proposed in the literature. For the MAX8 designer peptide, we will present direct evidence of proposed β-hairpin formation. For the SAF-p1/p2 system, we will show inter-molecular side chain contacts that are consistent with an α-helical coiled-coil nanofiber structure. We will use these results to evaluate our overall ability to predict and control self-assembled peptide molecular structures.

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