Studies of Bitter Peptides from Casein Hydrolyzate. I. Synthesis of Bitter Peptide BPIa Corresponding to Arg–Gly–Pro–Pro–Phe–Ile–Val from Casein Hydrolyzate by Alkaline Proteinase of Bacillus subtilis

A bitter heptapeptide BPIa was synthesized and compared with the natural peptide, isolated by Minamiura et al. from casein hydrolyzate, by means of thin layer chromatography, paper electrophoresis, and carboxymethylcellulose column chromatography. All results for the two peptides matched very closely each other. The synthetic BPIa has an extremely bitter taste with its threshold value 0.05 mM. It is one of the most bitter compounds such as phenylthiourea and quinine.