Tryptophan-rich antimicrobial peptides: properties and applications

There is a world-wide quest for development of new-generation antibiotics, due to the emergence of microbial pathogens that have developed resistance to the currently available antibiotics. The antimicrobial peptides (AMPs) are a strong candidate in this regard, due to minimal possibilities of emergence of resistance against these. The tryptophan (Trp)-rich peptides comprise an important class of AMPs. The amino acid Trp has unique biochemical properties that allow it to interact with and insert into biological membranes. This feature, together with the presence of basic residues in many AMPs that enable selective binding to microbial membranes, imparts strong antimicrobial properties on Trp-rich peptides. Such peptides thus display activity against a range of bacteria, fungi and viruses, and some are also active against protozoan pathogens and/or cancer cells. The mechanisms of action of the peptides may involve cell lysis or intracellular effects. The applications of such AMPs range from human health and hygiene to plant pathogen control.