Self-assembling β-sheet tape forming peptides

Biological proteins have intrinsically the ability to self-assemble, and this has been implicated in pathological situations called amyloid diseases. Conversely understanding protein self-assembly and how to control it can open up the route to new nanodevices and nanostructured materials for a wide range of applications in medicine, chemical industry and nanotechnology. Biological peptides and proteins have complex chemical structure and conformation. This makes it difficult to decipher the fundamental principles that drive their self-assembling behaviours. Here we review our work on the self-assembly of simple de novo peptides in solution. These peptides are designed so that: (i) the chemical complexity of the primary structure and (ii) the conformational complexity are both kept to a minimum. Each peptide adopts an extended beta-strand conformation in solution and these beta-strands self-assemble in one dimension to form elongated tapes as well as higher order aggregates with pure antiparallel beta-sheet structure, without the presence of any other conformations such as turns, loops, alpha-helices or random coils. Experimental data of the self-assembling properties are fitted with an appropriate theoretical model to build a quantitative relationship between peptide primary structure and self-assembly. These simple systems provide us with the opportunity to reveal the generic properties of the pure beta-sheet structures and expose the underlying physicochemical principles that drive the self-assembling behaviour of this biological motif.