Quantitative Heterodimerization of Aromatic Peptides through Host-Enhanced Polar–π Interactions for On-Resin Recognition

Peptide dimerization plays an important role in both natural and artificial supramolecular systems. A major challenge to date is the quantitative heterodimerization of two peptides without formation of homodimers. Here, we employ a macrocyclic host to simultaneously encapsulate a canonical aromatic peptide and a non-canonical perfluorophenylalanine-containing peptide through polar–π interactions, thus forming an unprecedented new series of heteropeptide dimers with high binding affinity. This new peptide heterodimerization was applied to on-resin recognition and separation of aromatic peptides in a peptide mixture exhibiting over 95% isolation purity. This research unveils a generic approach to exploit quantitative heteropeptide dimers for the design of supramolecular (bio)systems.

Quantitative Heterodimerization of Aromatic Peptides through Host-Enhanced Polar–π Interactions for On-Resin Recognition

Peptide dimerization plays an important role in both natural and artificial supramolecular systems. A major challenge to date is the quantitative heterodimerization of two peptides without formation of homodimers. Here, we employ a macrocyclic host to simultaneously encapsulate a canonical aromatic peptide and a non-canonical perfluorophenylalanine-containing peptide through polar–π interactions, thus forming an unprecedented new series of heteropeptide dimers with high binding affinity. This new peptide heterodimerization was applied to on-resin recognition and separation of aromatic peptides in a peptide mixture exhibiting over 95% isolation purity. This research unveils a generic approach to exploit quantitative heteropeptide dimers for the design of supramolecular (bio)systems.

Development and Characterization of Polymeric Peptides for Antibody Tagging of Bacterial Targets

Background: Microbe-Binding Peptides (MBPs) are currently being investigated to address the problem of antimicrobial resistance. Strategies enhancing their antimicrobial activity have been developed, including peptide dimerization. Here, we present an alternative approach based on peptide polymerization, yielding hapten-labelled polymeric MBPs that mediate tagging of bacteria with anti-hapten antibodies, for enhanced immune recognition by host phagocytes. Methods: C-terminally amidated analogs of the bacterial-binding peptide IIGGR were synthesized, with or without addition of cysteine residues at both N- and C-termini. Peptides were subjected to oxidizing conditions in a dimethyl-sulfoxide/water solvent system, and polymerization was demonstrated using SDS-PAGE. Peptides were then N-terminally labelled with a trinitrophenyl (TNP) group using trinitrobenzene sulfonate (TNBS). Binding to representative bacteria was demonstrated by ELISA using anti-TNP antibodies and was quantified as half-maximal effective concentration (EC50). Minimum Inhibitory Concentration (MIC) and concentration yielding 50% hemolysis (H50) were estimated. Neutrophil phagocytic index was determined for TNP-labelled polymeric bacterial- binding peptide (Pbac) with anti-TNP antibodies and/or serum complement. Results: Polydisperse Pbac was synthesized. EC50 was lower for Pbac than for the corresponding monomeric form (Mbac), for both Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922. MIC and H50 were >250μg/mL for both Pbac and Mbac. A complement-independent increase in neutrophil phagocytic index was observed for E. coli treated with TNP-labelled Pbac in conjunction with anti-TNP antibodies. Conclusion: Our data suggest that hapten-labelled polymeric bacterial-binding peptides may easily be produced from even crude synthetic oligopeptide precursors, and that such bacterial-binding peptides in conjunction with cognate anti-hapten antibodies can enhance immune recognition of bacteria by host phagocytes.

Dimerization of Antimicrobial Peptides: A Promising Strategy to Enhance Antimicrobial Peptide Activity

Antimicrobial resistance is a global health problem with strong social and economic impacts. The development of new antimicrobial agents is considered an urgent challenge. In this regard, Antimicrobial Peptides (AMPs) appear to be novel candidates to overcome this problem. The mechanism of action of AMPs involves intracellular targets and membrane disruption. Although the exact mechanism of action of AMPs remains controversial, most AMPs act through membrane disruption of the target cell. Several strategies have been used to improve AMP activity, such as peptide dimerization. In this review, we focus on AMP dimerization, showing many examples of dimerized peptides and their effects on biological activity. Although more studies are necessary to elucidate the relationship between peptide properties and the dimerization effect on antimicrobial activity, dimerization constitutes a promising strategy to improve the effectiveness of AMPs.

Dimerization of the Antimicrobial Peptide Polyphemusin I into One Polypeptide Chain: Theoretical and Practical Consequences

A strategy of sequential dimerization of monomers of antimicrobial peptides (AMPs) into one polypeptide chain has been implemented on the example of a beta-structural AMP polyphemusin I which is one of the most effective candidate for use as an antibiotic. The possible polyphemusin I monomer and dimer structures in lipid membrane were studied in this work via molecular modeling. To this end, these molecules were chemically synthesized so that the dimer represented two monomers connected in series into one polypeptide chain with a flexible linker. The antimicrobial effects of monomer and dimer were then tested on various bacterial cultures, and their similarity was shown. Therefore, we can conclude that the pore formation is not a putative mechanism of the polyphemusin I action. antimicrobial peptides, peptide dimerization, mechanism of antimicrobial action, polyphemusin The work was supported by the Ministry of Science and Higher Education of the Russian Federation (Project Unique Identifier RFMEFI57517X0151).