877754-71-7Relevant articles and documents
Site-Specific Incorporation of Selenocysteine Using an Expanded Genetic Code and Palladium-Mediated Chemical Deprotection
Liu, Jun,Zheng, Feng,Cheng, Rujin,Li, Shanshan,Rozovsky, Sharon,Wang, Qian,Wang, Lei
, p. 8807 - 8816 (2018)
Selenoproteins containing the 21st amino acid selenocysteine (Sec) exist in all three kingdoms of life and play essential roles in human health and development. The distinct low pKa, high reactivity, and redox property of Sec also afford unique routes to protein modification and engineering. However, natural Sec incorporation requires idiosyncratic translational machineries that are dedicated to Sec and species-dependent, which makes it challenging to recombinantly prepare selenoproteins with high Sec specificity. As a consequence, the function of half of human selenoproteins remains unclear, and Sec-based protein manipulation has been greatly hampered. Here we report a new general method enabling the site-specific incorporation of Sec into proteins in E. coli. An orthogonal tRNAPyl-ASecRS was evolved to specifically incorporate Se-allyl selenocysteine (ASec) in response to the amber codon, and the incorporated ASec was converted to Sec in high efficiency through palladium-mediated cleavage under mild conditions compatible with proteins and cells. This approach completely obviates the natural Sec-dedicated factors, thus allowing various selenoproteins, regardless of Sec position and species source, to be prepared with high Sec specificity and enzyme activity, as shown by the preparation of human thioredoxin and glutathione peroxidase 1. Sec-selective labeling in the presence of Cys was also demonstrated on the surface of live E. coli cells. The tRNAPyl-ASecRS pair was further used in mammalian cells to incorporate ASec, which was converted into Sec by palladium catalyst in cellulo. This robust and versatile method should greatly facilitate the study of diverse natural selenoproteins and the engineering of proteins in general via site-specific introduction of Sec.
Chemical and Ribosomal Synthesis of Topologically Controlled Bicyclic and Tricyclic Peptide Scaffolds Primed by Selenoether Formation
Yin, Yizhen,Fei, Qianran,Liu, Weidong,Li, Zhuoru,Suga, Hiroaki,Wu, Chuanliu
supporting information, p. 4880 - 4885 (2019/03/17)
Bicyclic and tricyclic peptides have emerged as promising candidates for the development of protein binders and new therapeutics. However, convenient and efficient strategies that can generate topologically controlled bicyclic and tricyclic peptide scaffolds from fully-unprotected peptides are still much in demand, particularly for those amenable to the design of biosynthetic libraries. In this work, we report a reliable chemical and ribosomal synthesis of topologically controlled bicyclic and tricyclic peptide scaffolds. Our strategy involves the combination of selenoether cyclization followed by disulfide or thioether cyclization, yielding desirable bicyclic and tricyclic peptides. This work thus lays the foundation for developing peptide libraries with controlled topology of multicyclic scaffolds for in vitro display techniques.
Chemoselective modifications for the traceless ligation of thioamide-containing peptides and proteins
Wang, Yanxin J.,Szantai-Kis, D. Miklos,Petersson, E. James
supporting information, p. 6262 - 6269 (2016/07/11)
Thioamides are single-atom substitutions of canonical amide bonds, and have been proven to be versatile and minimally perturbing probes in protein folding studies. Previously, our group showed that thioamides can be incorporated into proteins by native chemical ligation (NCL) with Cys as a ligation handle. In this study, we report the expansion of this strategy into non-Cys ligation sites, utilizing radical initiated desulfurization to "erase" the side chain thiol after ligation. The reaction exhibited high chemoselectivity against thioamides, which can be further enhanced with thioacetamide as a sacrificial scavenger. As a proof-of-concept example, we demonstrated the incorporation of a thioamide probe into a 56 amino acid protein, the B1 domain of Protein G (GB1). Finally, we showed that the method can be extended to β-thiol amino acid analogs and selenocysteine.
