peptide cyclization strategies coupling a thiol to the C-terminal - Macrocyclization of peptides Peptide cyclization is a frequent strategy for mimicry of secondary structure Mastering Peptide Cyclization Strategies for Enhanced Stability and Bioactivity

Head-to-tailcyclizationof peptides Peptide cyclization strategies are revolutionizing the field of peptide therapeutics and research by offering methods to transform linear peptides into cyclic structures.作者：BS Nunez·2021—The aim of this study is to explore an alternative strategy that utilizesbiocatalysisas a method of achieving successful peptide cyclization. This transformation is not merely cosmetic; it imbues peptides with enhanced properties such as improved metabolic stability, increased bioavailability, and heightened receptor binding affinity, making them more potent and effective.Three Methods for Peptide Cyclization Via Lactamization The pursuit of these enhanced properties has led to the development of diverse state-of-the-art macrocyclization methodologies and techniques for peptides and peptidomimetics.

At its core, peptide cyclization involves forming a covalent bond to close the peptide chain, creating a ring structure. This can be achieved through various approaches, broadly categorized as chemical, enzyme and protein tag approachesStrategies for peptide macrocyclization: head to tail .... Each of these methods presents its own set of strengths and limitations, catering to different synthetic needs and peptide chemistries.

One of the most prevalent and widely studied strategies is head-to-tail cyclization, also referred to as backbone head-to-tail cyclization. This approach forms a peptide bond between the N-terminal amine and the C-terminal carboxyl group of a linear peptide. This method is particularly valuable for stabilizing the conformation of bioactive peptides and is a key component in many cyclic peptide synthesis strategies.

Beyond the backbone, macrocyclization between head, tail or sidechains offers further avenues for structural diversification and property modulation. This includes strategies that involve the peptide's side chains. For instance, side-chain to side-chain in situ peptide cyclization has emerged as an efficient and green procedure, often conducted under physiological conditionsCyclization Strategies in Peptide Derived Drug Design. Another significant approach is disulfide cyclization, which leverages the formation of a disulfide bond between cysteine residues作者：Y Ding·2024·被引用次数：9—Using relatively low boiling point solventssuch as ethyl acetate or acetonitrile as cosolvents provides an additional advantage over other .... Alternatively, thiol alkylation can be employed, often involving the coupling of a thiol to the C-terminal residue while the peptide is anchored to a resin.作者：ML Merz·2024·被引用次数：105—In this study, we developed a combinatorial synthesis and screening approach based on sequentialcyclizationand one-potpeptideacylation and screening. Specific chemical reagents can also facilitate this, such as using a chemical linker containing two or more methyl bromide groups which react with thiol groups of cysteine residues.Peptide Modifications; Cyclization; Stapled peptides

Macrolactamization is another critical strategy for forming cyclic peptides, involving the creation of a lactam ringPeptide Cyclization at High Concentration - The Raj Group. This can be achieved through solution-phase macrocyclization following solid-phase synthesis, or through direct coupling in the solution phase, though the latter can present challenges. To overcome potential hurdles, innovative techniques have been developed, such as employing an imine-induced ring-closing strategy to address high energy barriers associated with cyclization.

The choice of solvent can also play a crucial role in the efficiency of peptide cyclizationMacrocyclization has become a common approach forimproving the pharmacological properties and bioactivity of peptides. A variety of ribosomal-derived and non- .... For example, using relatively low boiling point solvents such as ethyl acetate or acetonitrile as co-solvents can offer advantages over other methodsMacrocyclization strategies for the total synthesis of cyclic depsipeptides. Furthermore, the strategic placement of specific amino acid residues can significantly impact cyclization yieldsRecent advances in peptide macrocyclization strategies. Research has shown that placing a pseudoproline close to the centre of the linear peptide can be an effective strategy to increase cyclization yield.Cyclic Peptides: Properties, synthesis, and applications

The development of novel peptide cyclization methods is an active area of research, driven by the desire to create cyclic peptides with improved pharmacological properties and bioactivity.作者：ML Merz·2024·被引用次数：105—In this study, we developed a combinatorial synthesis and screening approach based on sequentialcyclizationand one-potpeptideacylation and screening. This includes exploring key strategies for biocompatible peptide macrocyclisation and leveraging biocatalysis as an alternative method for achieving successful peptide cyclization. Researchers are also developing efficient two-step strategies to access macrocyclic peptides, often involving the programmed modification of specific residues like cysteine.

The significance of these peptide cyclization strategies cannot be overstated. They are instrumental in the development of therapeutic peptide leads with improved metabolic stability properties. Cyclic peptides exhibit advantages in binding protein targets with high affinity, making them promising candidates for inhibiting protein-protein interactions and for cyclic peptides for drug development. Ultimately, peptide cyclization is a frequent strategy for mimicry of secondary structure and the creation of conformational stability, leading to macrocyclic peptides with enhanced therapeutic potential. The ongoing exploration of diverse state-of-the-art macrocyclization methodologies and techniques promises to further expand the toolbox available to chemists and drug developers.