Abstract
It is well known that D-glutamic acid (D-Glu) is a major compound in poly-γ-glutamic acid (PGA) which is one of the major components in the viscous substances of Natto. However, no information has been obtained for the existence of D-amino acids except for D-Glu in Natto. Thus, D-amino acids were widely surveyed using the combination method of TLC and HPLC for the amino acid derivatives synthesized by reacting FDAA (fluoro-dinitrophenyl-L-Ala-NH2) with amino acids in the water-soluble fraction of the viscous parts of Natto.
The results obtained in this study were as follows:(1) D-aspartic acid (D-Asp) and D-alanine (D-Ala) as well as D-Glu were detected in the viscous parts.(2) D-Glu was found not only in the conjugated form but also in the free form. However, D-Asp was only in the conjugated form and most of D-Ala was in the free form.(3) The content of the conjugated D-Glu was 3mmole per 100g Natto or more, while those of the free DGlu, conjugated D-Asp and free D-Ala were 0.5 mmole per 100g Natto or less.
