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With the new heptapeptides, researchers from the IBB-UAB demonstrate that only four different types of amino acids, distributed in a specific manner and combined always with another fifth type, are enough to obtain the complete code needed to form synthetic prion fibers.

In the study, researchers verified the stability and functionality of the four fabricated peptides. They built one of the most degradation-resistant biological nanomaterials described to date, nanocables covered in silver which can act as electrical nanoconductors and fibrillar mini enzymes capable of acting as catalysts in the formation of organic nanomaterials.

The new molecules have numerous applications, but researchers aim to focus on “the generation of electrical nanoconductors, and make use of the knowledge of the amyloid structure to generate synthetic fibers capable of being catalysts for new chemical reactions. The final objective will be to generate hybrid peptide-inorganic materials capable of making complex reactions, as those created by the photosystems of plants," the IBB researcher points out.

In order to generate new peptides, IBB researchers based their work on specific sequences of prion proteins, known as prion domains (PrDs). “We studied which amino acids are more frequent and how they are distributed in these regions, demonstrating that only four different types of amino acids distributed in a specific manner and always combined by a fifth type of amino acid is sufficient to have the complete code needed to form synthetic prion fibers. In fact, each of the heptapeptides (mini-PrDs) designed only contains two different types of amino acids,” says Ventura.

The study demonstrates the assembling ability of mini-PrDs into highly ordered nanostructures, a process thought to be impossible given the large presence of polar amino acids. The resulting peptides are more polar than any other similarly sized peptide used until now to form synthetic amyloids; this, for example, allows them to function in the same conditions as natural enzymes.

The peptides assemble to form miniature enzymes capable of acting as catalysts in the formation of nanomaterials such as the conductive polymer polypyrrole.

This study has served to help researchers of the IBB Protein Folding and Conformational Diseases group, directed by Dr Ventura, to open a new line of research focused on the design of nanomaterials.

“We have never worked on nanotechnology, but at the same time we have always had it near, because our strength lies in the knowledge of the molecular mechanism of protein assembly into amyloid structures. For a long time we have been working to create strategies with which to avoid this phenomenon in neurodegenerative diseases. This knowledge has allowed us to design new molecules which we now propose for the fabrication of new nanomaterials,” Ventura concludes.

Source: Universitat Autònoma de Barcelona

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