Amino acids, peptides and proteins is a series of specialist periodical reports published as independent volumes that provides a comprehensive overview of contemporary research in protein science from amino acids through peptides to macromolecular assemblies. Since its launch in 1969, the series has covered diverse developments in the chemistry, biology and application of amino acids, peptides and proteins, bringing new and established science together. Each volume in the series strives to review literature published over the last few years, providing also the overview of underpinning concepts and terminology wherever appropriate.

The 45th volume of the series discusses the latest research in protein synthesis, modulation of microtubule function by peptides, and nanostructure construction by protein self-assembly. In particular, an emphasis is made on structure–function relationships and how these can be exploited to rationally design functional architectures at the nanoscale. The volume opens with a chapter on a total chemical protein synthesis achieved using single or multiple ligation reactions of synthetic peptide segments (Hayashi et al.), which to this date remains a challenging endeavour. Both naturally occurring and designed proteins were synthesized by the sequential ligation of three or more peptide segments without purification and isolation of intermediate peptides, which led to an effective approach of a one-pot multiple peptide ligation. The range of target proteins which have been produced using chemical protein synthesis is expanding thanks to advances in the development of one-pot ligation chemistries. Chemical synthesis is instrumental for investigating the function, structure, and stability of natural and artificial proteins, and is expected to provide decisive solutions to the elucidation of structure–function relationships in proteins. The second chapter addresses the functionalization of microtubules by Tau-derived peptides which selectively binds to the inside of microtubules (Inaba et al.). Microtubules, natural tubular protein assemblies, serve various roles in cells as cytoskeletons. They also constitute important targets to study and manipulate cellular mechanisms as well as interesting building blocks for dynamic nanomaterials. The structure, stability, motility, and superstructures of microtubules can be modulated by Tau-derived peptides and their conjugates with proteins or other nanoscale materials. This ability to modify and reconstruct microtubules holds promise for biological and nanotechnological applications. The topic of protein self-assembly continues in the next chapter which looks into the self-assembly of designed proteins forming cage-like containers such as viral capsids (Heddle et al.). The progress in the area is exemplified using re-engineered tryptophan RNA-binding attenuation protein (TRAP) rings which self-assemble into thermostable TRAP cages via coordination of gold ions. To provide an application, TRAP cages can be modified with cell-penetrating peptides to enable the development of reduction-responsive drug delivery systems into cells. The fourth chapter provides an unconventional focus on the self-assembly of designed peptides (Miki et al.). Instead of constructing assemblies first and then introducing them into living cells, this chapter discusses the self-assembly of designed peptides in living cells. For example, the self-design of coiled-coil or β-sheet forming peptides is shown to control the spatial arrangement of functional proteins within cells. This capability opens up a plethora of exciting possibilities. Controlling the dynamics of peptide assembly in living cells enables the creation of complex and “living” biomolecular systems, which are expected to underpin a toolbox for cell engineering and engineering biology. The final chapter reviews self-assembly of cyclic peptides and pseudo-cyclic peptides (Lim et al.). This largely underexplored area investigates the impact of cyclisation and consequently reduced conformational freedom of peptides on self-assembly and the generation of highly thermostable, homogeneous and unique molecular nanoscale assemblies, when compared with those of linear peptides. Examples of where such assembles can be applied include the control of the properties of non-biological materials such as carbon nanotubes, improved stabilisation and multivalent display of α-helical ligands, and the predictable design of nanostructures as drug delivery systems.

Kazunori Matsuura and Maxim Ryadnov