Epimerization-free synthesis of cyclic peptide by use of the O-acyl isopeptide method

Total Synthesis and Structural Characterization of Caveolin-1

Caveolin-1, which is an essential protein for caveola formation, was chemically synthesized. It is composed of 177 amino acid residues, is triply palmitoylated at the C-terminal region, and is inserted into the lipid bilayer to form a V-shaped structure in the middle of the polypeptide chain. The entire sequence was divided into five peptide segments, each of which was synthesized by the solid-phase method. To improve the solubility of the C-terminal region, O-acyl isopeptide structures were incorporated. After ligation by the thioester method and the introduction of the palmitoyl groups, all the protecting groups were removed and the isopeptide structures were converted into the native peptide bond. Finally, the obtained polypeptide was successfully inserted into bicelles, thus showing the success of the synthesis.

A Global Review on Short Peptides: Frontiers and Perspectives

Peptides are fragments of proteins that carry out biological functions. They act as signaling entities via all domains of life and interfere with protein-protein interactions, which are indispensable in bio-processes. Short peptides include fundamental molecular information for a prelude to the symphony of life. They have aroused considerable interest due to their unique features and great promise in innovative bio-therapies. This work focusing on the current state-of-the-art short peptide-based therapeutical developments is the first global review written by researchers from all continents, as a celebration of 100 years of peptide therapeutics since the commencement of insulin therapy in the 1920s. Peptide "drugs" initially played only the role of hormone analogs to balance disorders. Nowadays, they achieve numerous biomedical tasks, can cross membranes, or reach intracellular targets. The role of peptides in bio-processes can hardly be mimicked by other chemical substances. The article is divided into independent sections, which are related to either the progress in short peptide-based theranostics or the problems posing challenge to bio-medicine. In particular, the SWOT analysis of short peptides, their relevance in therapies of diverse diseases, improvements in (bio)synthesis platforms, advanced nano-supramolecular technologies, aptamers, altered peptide ligands and in silico methodologies to overcome peptide limitations, modern smart bio-functional materials, vaccines, and drug/gene-targeted delivery systems are discussed.

Recent Reports of Solid-Phase Cyclohexapeptide Synthesis and Applications

Macrocyclic peptides are privileged scaffolds for drug development and constitute a significant portion of macrocyclic drugs on the market today in fields spanning from infectious disease to oncology. Developing orally bioavailable peptide-based drugs remains a challenging task; however, macrocyclization of linear peptides can be an effective strategy to improve membrane permeability, proteolytic stability, oral bioavailability, and overall drug-like characteristics for this class. Significant advances in solid-phase peptide synthesis (SPPS) have enabled the efficient construction of macrocyclic peptide and peptidomimetic libraries with macrolactamization being performed on-resin or in solution phase. The primary goal of this review is to summarize solid-phase cyclohexapeptide synthesis using the on-resin and solution-phase macrocyclization methodologies published since 2013. We also highlight their broad applications ranging from natural product total synthesis, synthetic methodology development, and medicinal chemistry, to drug development and analyses of conformational and physiochemical properties.