Synthesis and peptide binding properties of methoxypyrrole amino acids (MOPAS).

[structure: see text] Methoxypyrrole amino acids (MOPAS) have been prepared and were introduced into small peptides with hairpin structures. The intra- and intermolecular binding properties of this heterocyclic amino acid mimicking a dipeptido beta-strand was investigated by NMR titration and X-ray crystal structure analysis. The data reveal a hydrogen bonding pattern that is complementary to a peptide beta-sheet.