Figure 3.

Synthetic data. (A) Kinetically controlled ligation between 1–33:COSΦCH₂COOH and Cys34–52:COSR resulted in one major product; subsequent alkylation with ICH₂CONH₂ resulted in the expected mass shift of 72 Da (inset). (B) The final native chemical ligation reaction between 1–52:COSR and Cys53–70 was complete at 22 h, with the major product the full-length synthetic KChIP2d. (C) Purified synthetic KChIP2d after preparative reverse-phase HPLC. Observed mass: 8421 ± 2 Da; Calculated mass (average isotopes): 8418.6 Da.