Bitterness of Diastereomers of a Hexapeptide (Arg-Arg-Pro-Pro-Phe-Phe) Containing D-Phenylalanine in Place of L-Phenylalanine

Abstract

In order to investigate the steric requirement of the C-terminal hydrophobic amino acid of the bitter peptide, Arg-Arg-Pro-Pro-Phe-Phe, for the production of bitterness, we prepared analogs of it containing o-phenylalanine, in place of L-phenylalanine. The analogs with L-phenylalanine at the C-terminal exhibited stronger bitterness than those with D-phenylalanine at the C-terminal. We confirmed that the configuration of the C-terminal hydrophobic amino acid is important for the increase in bitterness.