Fig. 14.

Schematic diagram of the uncatalyzed and catalyzed routes to ligation for a self-replicating peptide. The condensation reaction of the substrate molecules S₁ and S₆ is greatly facilitated by their colocalization by the catalyst E (rate k₃). Residues critical for molecular recognition and ligation are shown colored (red, glutamic acid; blue, lysine and arginine; yellow, cysteine; gray, leucine and valine).

Reproduced with permission from Severin et al.⁶⁶ copyright Nature Publishing Group (1997).