Chemoselective Copper-Mediated Modification of Selenocysteines in Peptides and Proteins

Abstract

Highly valuable bioconjugated molecules must be synthesized through efficient, chemoselective chemical modifications of peptides and proteins. Herein, we report the chemoselective modification of peptides and proteins via a reaction between selenocysteine residues and aryl/alkyl radicals. In situ radical generation from hydrazine substrates and copper ions proceeds rapidly in an aqueous buffer at near neutral pH (5–8), providing a variety of Se-modified linear and cyclic peptides and proteins conjugated to aryl and alkyl molecules, and to affinity label tag (biotin). This chemistry opens a new avenue for chemical protein modifications.

Chemical synthesis of human selenoprotein F and elucidation of its thiol-disulfide oxidoreductase activity

“…We envision that the chemistries relating to the selective desulfurization in the presence of Sec and simultaneous Acm/Mob removal disclosed herein may find further applications in the CPS field, where the use of Sec either for selenoprotein synthesis or as a Cys analogue, has become an increasingly popular strategy. 28,32,46…”

“…We envision that the chemistries relating to the selective desulfurization in the presence of Sec and simultaneous Acm/Mob removal disclosed herein may nd further applications in the CPS eld, where the use of Sec either for selenoprotein synthesis or as a Cys analogue, has become an increasingly popular strategy. 28,32,46 The second ligation between peptide 1 and 6 was carried out in the presence of 0.1 M ascorbate and a reduced concentration of TCEP (5 mM) to prevent the now-free selenol side-chain from being removed, [47][48][49] furnishing the full-length protein 7. Aer 12 h, the ligation mixture was directly subjected to folding trials.…”

“…14,15 The development of expressed protein ligation (EPL) technologies has further powered the synthesis of (especially) large proteins. 16,17 A number of native selenoproteins and Sec-containing analogue proteins have thus been generated by CPS, as listed in Table S1 † 18–30 . Despite these significant achievements, the currently used synthetic routes usually involve either no or limited post-ligation treatment, as a result most of the synthetic Sec-proteins either are small in size (usually <100 aa and with few Cys/Sec residues) or contain a Sec residue at the C-terminal region, which can be obtained by EPL through ligation with a synthetic peptide bearing an N-terminus Sec (Table S1,† entries 4, 8 and 11).…”

“…16,17 A number of native selenoproteins and Sec-containing analogue proteins have thus been generated by CPS, as listed in Table S1. † [18][19][20][21][22][23][24][25][26][27][28][29][30] Despite these signicant achievements, the currently used synthetic routes usually involve either no or limited post-ligation treatment, as a result most of the synthetic Sec-proteins either are small in size (usually <100 aa and with few Cys/Sec residues) or contain a Sec residue at the C-terminal region, which can be obtained by EPL through ligation with a synthetic peptide bearing an Nterminus Sec (Table S1, † entries 4, 8 and 11). As such, there is a clear need to develop a more straight-forward strategy for the synthesis of complex selenoproteins having multiple Cys and Sec residues, like in the case of SelF (7 Cys and 1 Sec).…”

Organometallic S-arylation Reagents for Rapid PEGylation of Biomolecules

“…This strategy could allow for conjugation of polymers to proteins with limited stability at room temperature or which are only stable or soluble at non-neutral pH for the exploration of new biologics for therapeutic applications. Overall, this work represents an expansion of the growing organometallic reagent toolkit available for bioconjugation chemistry. ,,− …”