The Bitter Peptide in Natto

Abstract

The extract from Natto with n-butanol was separated into bitter peptide-rich fractions and some other fractions by Sephadex G-25 gel-filtration and ion-exchange resin chromatography on CM-Sephadex. The main peptide component was subjected to further purification by high voltage paper electrophoresis. The major spot of peptide on the electropherogram was cut off, and eluted with 10% acetic acid. The amino acid composition of purified peptide was Asp 1, Thr 1, Glu 1, Ala 1, Pro 2, Val 3, Ile 3 and Leu 5. amino acid sequence of the purified peptide was determined by DNP method for N-terminal and Carboxypeptidase A method for C-terminal sequence. The N-terminal amino acid of the peptide was found to be Leu and the C-terminal sequence of the peptide was -Ala-Val-Ile-Leu.