Artificial peptides with unnatural components designed for materializing protein function

In order to design functional peptides, we employed two strategies. The first one is to incorporate rigid unnatural amino acids into peptides to make the peptide backbone rigid. Functions were expected to appear through the conformational control by the strategy. A series of cyclic peptides constituted of alternating natural amino acids and 3-aminobenzoic acid, used as an unnatural amino acid, were synthesized. These cyclic peptides were found to function as strong binders for phosphomonoester, catalysts for ester hydrolysis, and/or ion channels. The second strategy is to conjugate peptides with unnatural and inherently functional molecules. Following this strategy, oligo(L-leucine)- or oligo(L-phenylalanine)-modified ruthenium tris(bipyridine) complexes were synthesized. Distance dependence of the photoinduced electron transfer from the ruthenium complexes and the function as sensors for phosphate anion (H(2)PO(-)(4)) are discussed.