Total Chemical Synthesis of Aggregation-Prone Disulfide-Rich Starfish Peptides.

A relaxin-like gonad-stimulating peptide (RGP), Aso-RGP, featuring six cysteine residues, was identified in the Crown-of-Thorns Starfish (COTS, Acanthaster cf. solaris) and initially produced through recombinant yeast expression. This method yielded a single-chain peptide with an uncleaved C-peptide (His Tag) and suboptimal purity.

Engineering of a Biologically Active Glycosylated Glucagon-Like Peptide-1 Analogue.

Glucagon-like peptide receptor (GLP-1R) agonists (e.g., semaglutide, liraglutide, etc.

Glycosylation Improves the Proteolytic Stability of Exenatide.

Exenatide was the first marketed GLP-1 receptor agonist for the treatment of type 2 diabetes. Modification to the chemical structure or the formulation has the potential to increase the stability of exenatide. We introduced human complex-type sialyloligosaccharide to exenatide at the native Asn28 position.

Total Chemical Synthesis of Palmitoyl-Conjugated Insulin.

Commercially available insulins are manufactured by recombinant methods for the treatment of diabetes. Long-acting insulin drugs (e.g.

Optimizing the Semisynthesis towards glycosylated interferon-β-polypeptide by utilizing bacterial protein expression and chemical modification.

The synthesis of a sufficient amount of homogeneous glycoprotein is of great interest because natural glycoproteins show considerable heterogeneity in oligosaccharide structures, making the studies on glycan structure-function relationship difficult. Herein, we report optimized methods that can accelerate the semisynthesis of homogeneous glycoproteins based on recombinant expression and chemical conversion. Peptide thioesters and peptides with Cys residues at their N-terminals are necessary intermediates to perform native chemical ligation.

Semisynthesis of a Homogeneous Glycoprotein Using Chemical Transformation of Peptides to Thioester Surrogates.

Semisynthesis using recombinant polypeptides as building blocks is a powerful approach for the preparation of proteins with a variety of modifications such as glycosylation. The activation of the C terminus of recombinant peptides is a key step for coupling peptide building blocks and preparing a full-length polypeptide of a target protein. This article reports two chemical approaches for transformation of the C terminus of recombinant polypeptides to thioester surrogates.

Chemical Synthesis and Characterization of a Nonfibrillating Glycoglucagon.

The current commercially available glucagon formulations for the treatment of severe hypoglycemia must be reconstituted immediately prior to use, owing to the susceptibility of glucagon to fibrillation and aggregation in an aqueous solution. This results in the inconvenience of handling, misuse, and wastage of this drug. To address these issues, we synthesized a glycosylated glucagon analogue in which the 25th residue (Trp) was replaced with a cysteine (Cys) and a Br-disialyloligosaccharide was conjugated at the Cys thiol moiety.

Chemical Glycosylation and Its Application to Glucose Homeostasis-Regulating Peptides.

Peptides and proteins are attractive targets for therapeutic drug development due to their exquisite target specificity and low toxicity profiles. However, their complex structures give rise to several challenges including solubility, stability, aggregation, low bioavailability, and poor pharmacokinetics. Numerous chemical strategies to address these have been developed including the introduction of several natural and non-natural modifications such as glycosylation, lipidation, cyclization and PEGylation.

Chemical Modification of the N Termini of Unprotected Peptides for Semisynthesis of Modified Proteins by Utilizing a Hydrophilic Protecting Group.

A simple and efficient strategy for the selective modification of the peptide N terminus with an unnatural amino acid is described. A peptide having a SUMO-HisTag-TEV sequence (SUMO: small ubiquitin-related modifier, TEV: tobacco etch virus) preceding the N terminus of the target peptide was designed. Recombinant expression in E.