title: Imidazole-Aided Native Chemical Ligation: Imidazole as a One-Pot Desulfurization-Amenable Non-Thiol-Type Alternative to 4-Mercaptophenylacetic Acid.
abstract: Various bioactive proteins have been synthesized by native chemical ligation (NCL) and its combination with subsequent desulfurization (e.g., conversion from Cys to Ala). In NCL, excess 4-mercaptophenylacetic acid (MPAA) is generally added to facilitate the reaction. However, co-elution of MPAA with the ligation product during preparative high-performance liquid chromatography sometimes reduces its usefulness. In addition, contamination of MPAA disturbs subsequent desulfurization. Here, we report for the first time that imidazole can be adopted as an alternative to MPAA in NCL using a peptide-alkylthioester. The efficiency of the imidazole-aided NCL (Im-NCL) is similar to that of traditional MPAA-aided NCL. As model cases, we successfully synthesized adiponectin(19-107) and [Ser(PO3H2)65]-ubiquitin using Im-NCL with a one-pot desulfurization.
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Sakamoto
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Shugo
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Mochizuki
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Yukie
authors.initials: Y
authors.lastname: Nohara
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Nishio
authors.affiliation: Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki-shi, Osaka, 567-0085, Japan.
authors.forename: Taku
authors.identifier: http://orcid.org/0000-0002-7276-5614
authors.initials: T
authors.lastname: Yoshiya
keywords: chemical protein synthesis; desulfurization; imidazole; native chemical ligation; thiol additive free