Exploring the self-assembly of a short aromatic Aβ(16-24) peptide.

The use of self-assembling peptides as scaffolds for creating biomaterials has prompted the scientific community to carry out studies on short peptides as model systems. Short peptides help in dissecting contributions from different interactions, unlike large peptides, where multiple interactions make it difficult to dissect the contributions of individual interactions. This opens avenues for fine tuning peptides to carry out a wide range of physical or chemical properties. In this line of study Aβ(16-24) is a versatile building block not only as a scaffold for creating biomaterials but also because it forms the active core in the protein that forms amyloid plaques. In this study, we probe the self-assembly of peptide Aβ(16-24) using fluorescence spectroscopy, circular dichroism, isothermal titration calorimetry, transmission electron microscopy, and atomic force microscopy. The process of self-assembly is dictated by the burial of phenyl alanines in the hydrophobic core and guided by nonbonding interactions and H-bonding. The process of fibril formation is enthalpically driven, and the fibrils showed blue and green luminescence without the addition of any external agent or sensitizer. Because these short peptides are known to bind with fully formed amyloid fibrils, this opens a route to the study of amyloid systems in vitro or isolated from patients suffering from Alzheimer's disease.