Polypeptide self-assembly surfaces

This chapter describes the self-assembly of non-native protein fibers known as amyloid fibrils and the development of these fibrils for potential applications in nanotechnology and biomedicine. It extends an earlier review by the author on a related topic (Gras, 2007). In Section 1, the self-assembly of polypeptides into amyloid fibrils and efforts to control assembly and any subsequent disassembly are discussed. In Section 2, this review focuses on the important role of surfaces and interfaces during and after polypeptide assembly. It examines how different surfaces can influence fibril assembly, how surfaces can be used to direct self-assembly in order to create highly ordered structures, and how different techniques can be used to create aligned and patterned materials on surfaces following self-assembly. 

An understanding of the interaction between polypeptides and surfaces is imperative if self-assembly is to be achieved in a reproducible manner. This is especially important if the scale of assembly is to be increased from small-scale laboratory experiments to larger reaction vessels. Insights obtained into surface-based assembly can also be used to design surface-based "reactor platforms" which encourage surface interactions in order to achieve... 

Hydrophobic and osmophobic effects are important not only in the folding of individual polypeptide chains into compact globular proteins, but also in the assembly of multiprotein complexes. Osmophobic effects are noted, for instance, in the self-assembly of subunits of the glycolytic enzyme phosphofructokinase (PFK). Self-assembly is enhanced by the presence of stabilizing organic cosolvents such as trimethylamine-A-oxide (TMAO) (Hand and Somero, 1982). As discussed later, self-assembly driven by osmophobic effects results from the thermodynamic favorability of minimizing the surface area on the proteins that is in contact with the cosolvent. 

Cysteine is one of the 20 common amino acids found in protein molecules (or 21 if selenocysteine is included). There has been interest in studying the interaction of amino acids with solid surfaces since they are expected to play a crucial role in the chemisorption of proteins and polypeptides. The redox electrochemistry of immobilized proteins, chiefly metalloenzymes, is of interest for biosensing applications and also fundamental studies of electron transfer. Self-assembled monolayers of cysteine have also themselves been used for the immobilization of proteins. The molecular structure of cysteine is shown in Fig. 7-10. In common with all other amino... 

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