Modular Building Blocks for Amino Acid Recognition in Peptides

A toolkit of tailor-made peptide receptors contains building blocks for polar, aromatic, and cationic amino acids. Dipeptides are stabilized in the β-sheet conformation by complexation with an aminopyrazole which carries a U-shaped substituent with a properly placed binding site at its tip (see picture). The additional interaction with the amino acid side chain leads to a tenfold increase in the association constant.