title: Macrocyclization and labeling of helix-loop-helix peptide with intramolecular bis-thioether linkage.
abstract: Conformationally constrained peptides have been developed as an inhibitor for protein-protein interactions (PPIs), and we have de novo designed cyclized helix-loop-helix (cHLH) peptide with a disulfide bond consisting of 40 amino acids to generate molecular-targeting peptides. However, synthesis of long peptides has sometimes resulted in low yield according to the respective amino acid sequences. Here we developed a method for efficient synthesis and labeling for cHLH peptides. First, we synthesized two peptide fragments and connected them by the copper-mediated alkyne and azide cycloaddition (CuAAC) reaction. Cyclization was performed by bis-thioether linkage using 1,3-dibromomethyl-5-propargyloxybenzene, and subsequently, the cHLH peptide was labeled with an azide-labeled probe. Finally, we designed and synthesized a peptide inhibitor for the p53-HDM2 interaction using a structure-guided design and successfully labeled it with a fluorescent probe or a functional peptide, respectively, by click chemistry. This macrocyclization and labeling method for cHLH peptide would facilitate the discovery of de novo bioactive ligands and therapeutic leads. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 415-421, 2016.
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Nishihara
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Kitada
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Fujiwara
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Fujii
mesh_terms: D057930:Click Chemistry / Q000379:methods*; D018257:Helix-Loop-Helix Motifs; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D010455:Peptides
keywords: inhibitors; labeling; ligation; macrocyclization; peptides