Protein engineering has traditionally relied upon the possibility of changing the primary structure by either site-directed mutagenesis or peptide synthesis. Recently the scope of these methods has been extended to non-natural amino acids by both biosynthetic and synthetic approaches. A further step in which a complete structural motif is replaced by an equivalent synthetic mimic has been validated in small peptides. We extend these results to the field of protein engineering by incorporating a beta-turn mimic into a small protein, scyllatoxin, which contains all major secondary structure elements. The synthetic scyllatoxin was structurally and functionally characterized and Pound to be equivalent to the native protein.