| Abstract
| - Poly(γ-glutamic acid) (PGA) produced by a strain of Bacillus subtilis was partially hydrolyzed into various oligopeptides so that the dipeptide fraction was isolated by the preparative thin-layer chromatography. HPLC analysis was applied to the detection of each of the four stereoisomers in this fraction using chemically synthesized authentic samples. The fraction consisted of N-γ-d-glutamyl-d-glutamic acid, N-γ-l-glutamyl-l-glutamic acid, N-γ-d-glutamyl-l-glutamic acid, and N-γ-l-glutamyl-d-glutamic acid at a ratio of 5.9:6.0:1.0:1.0. On the basis of this result, a model was proposed for the microstructure of the bacterial PGA, in which d- and l-glutamic acid repeating units are alternately linked in a single chain of the molecule.
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