Since 1969 this series of specialist periodical reports has covered the area of protein and peptide science without favouring topical polularity. This approach has helped to keep abreast with achievements in seemingly less acknowledged areas that would have limited coverage in the mainstream scientific literature. As any other series of this type these reports are presented as research accounts that evolve owing to emerging research areas. This volume continues the tradition of bringing new and established science together. The book reviewes literature predominantly published over the last three years, with each chapter providing fundamental concepts and terminology.

This 42nd volume opens with a detailed discussion of contemporary developments in the applied research of amino acids (Zarandi and Szolomajer). The review focuses on the chemistry, origin and physical properties of amino acids. It starts with naturally occuring derivatives, both l- and d-epimers, introducing fundamentals of structural diversity, which is logically followed by application highlights ranging from pharmaceuticals to food supplements. Mechanisms of biological action and biosynthetic routes towards particular derivatives are then described, bridging with chemical syntheses and low- and high-resolution analytical methods used for physico-chemical characterisation. The second chapter ramps up the discussion to the challenge of synthetic strategies for the bioconjugation of amino acids and peptides (Banoczi and Hudecz). Various bioconjugates are discussed as proven research tools and validated precursors for therapeutic agents. The chapter predominantly stresses the importance of synthetic and semi-synthetic approaches, explaining conjugation mechanisms and presenting linkers commonly used for ligation and labelling. Therapeutic agents are exemplified by conjugates with known biologically active peptide moieties including the cell-adhesion RGD motif and antimicrobial peptides. Selected areas of applications feature peptide conjugates as immunogens and cell-penetrating drug delivery systems. Mechanisms by which peptides interact with, cross or disrupt cellular membranes are given in the following chapter (Pfeil and Watts). This report tackles the challenge of elucidating inter- and intra-molecular interactions underpinning the biological function of antimicrobial peptides, synthetic and native. State-of-the-art NMR and EPR methods and innovative approaches are detailed with regards to solving lipid-peptide ensembles in membrane bilayers. The chapter links the conserved physicochemical parameters that are characteristic of antimicrobial peptides with the physical basis of their biological action. Structure-activity relationships of naturally occuring antimicrobial peptides are discussed in the following chapter (Falanga and Galdiero), which relates to the preceding report with an attempt to find a generic rationale for developing such peptides as drugs. The chapter gives a contemporary overview of recent and on-going efforts to commercialise antimicrobial peptides with specific references to drug developers active in the area. Pharmaceutical developments addressing the problem of infectious diseases are further discussed in the next chapter (Akaji), which reviews progress in the design of selective peptide-based ligands able to interact with 3C like proteases of coronaviruses. The chapter is written in a form of an R&D protocol that provides information as to the structure of the protein target, its function in viruses and mechanisms of its inhibition by a variety of peptidomimetics. Comparative efficacies of the peptidomimetics presented are tabulated into IC₅₀ values obtained against coronoviruses causing Severe Acute and Middle East Respiratory Syndromes (SARS and MERS, respectively). The chapter is built around the traditional concept of ligand–protein targeting, which remains key for pharmaceutical industry. A complementary strategy is presented in the closing chapter of the volume (Le Joncour and Laakkonen), which drives the topic of peptide-based drugs to exploiting the intrinsic properties of the peptides to specifically target cancer cells. Screening combinatorial technologies, e.g. phage displays, are discussed as effective discovery platforms for novel and highly selective peptides targeting tumour cells. The chapter outlines pros and cons of ex vivo, in vivo and in vitro screening approaches, highlighting technical issues that are critical for further progress. The chapter then concentrates on identified peptides with known and unknown targets and the application of these peptides for both tumour imaging and therapy. The report concludes the volume with a neat analogy of a Swiss-Army Knife relating to the multi-purpose function of peptides.

Maxim Ryadnov and Ferenc Hudecz