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. Author manuscript; available in PMC: 2020 Aug 7.
Published in final edited form as: Chem Commun (Camb). 2019 Jul 10;55(61):8959–8962. doi: 10.1039/c8cc10192b

Figure 1.

Figure 1.

Incorporation of α-Me-Cys by in vitro translation. (A) Sequence and cyclization of in vitro translated peptides containing α-Me-Cys. (B) MALDI-TOF MS spectrum of an in vitro translation of a peptide containing two α-Me-Cys residues. Expected [M+H]+: 1862.80. Observed [M+H]+: 1862.16. (C) MALDI-TOF MS spectrum after cyclization of the peptide in (B) with DBX. Expected [M+H]+:1964.85. Observed [M+H]+: 1964.36. (D) Peptide yield of an in vitro translation reaction (50 μL) of library mRNAs with two fixed valine codons in the presence of ValRS+Val, tRNAVal pre-charged with α-Me-Cys, or neither. The library was a mixture of three degenerate mRNAs: MXX*XXX*xrefGGGH6, MXXXX*XXX*XXXXGGGH6, and Mxref*XXX*XXGGGH6 where * = a fixed valine codon (GUA) and X’s are randomized (NNS) positions. Yield is measured by capture onto Ni-NTA beads using 35S-Met counting after background subtraction of a control reaction lacking mRNA.