2020 年 78 巻 2 号 p. 130-139
Chemical protein synthesis (CPS) that consists of solid-phase peptide synthesis and peptide ligation generates not only naturally-occurring proteins with/without posttranslational modifications (PTMs), but also a variety of artificial proteins including unnatural amino-acids such as ᴅ-amino acids and fluorophore-labeled amino acids. This unique property offers new analytical methods for protein structure and interaction in terms of PTMs. In fact, we have chemically synthesized histone proteins with PTMs, which play an important role in regulation of gene expression in eukaryotic cells, and analyzed the effects of PTMs such as methylation, acetylation, and phosphorylation. However, current CPS is still in developing process and includes several issues to be solved such as difficult handling in hydrophobic protein synthesis and time-consuming multistep process for large protein synthesis. We have approached these issues by creating new strategies for peptide ligation. One-pot ligation of five peptide segments was demonstrated for the first time by utilizing multifunctionality of thiophenol compound in deprotection of allyloxycarbonyl group by palladium complex. New thioester precursors for native chemical ligation, which have potential to offer a novel two-way one-pot ligation, have also been developed recently. Furthermore, we have been developing a new strategy for simultaneous ligation of multiple peptides on DNA scaffold, which can connect peptides in highly diluted condition. This article also describes the background and current situation of CPS with our future perspectives.