title: Rapid purification and plasticization of D-glutamate-containing poly-γ-glutamate from Japanese fermented soybean food natto.
abstract: Poly-γ-glutamate (PGA) is a major component of mucilage derived from natto, a Japanese fermented food made from soybeans, and PGAs obtained under laboratory's conditions contain numerous d-glutamyl residues. Natto foods are thus promising as a source for nutritionally safe d-amino acids present in intact and digested polymers, although there is little information on the stereochemistry of PGA isolated directly from natto. Here, we describe the development of a new process for rapid purification of PGA using alum and determined the D-glutamate content of natto PGA by chiral high-performance liquid chromatographic analysis. Further, using hexadecylpyridinium cation (HDP(+)), which is a compound of toothpaste, we chemically transformed natto PGA into a new thermoplastic material, called DL-PGAIC. (1)H nuclear magnetic resonance and calorimetric measurements indicate that DL-PGAIC is a stoichiometric complex of natto PGA and HDP(+) with glass transition points of -16.8 °C and -3.1 °C. Then, DL-PGAIC began decomposing at 210°C, suggesting thermal stability suitable for use as a supramolecular soft plastic.
authors: Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan; Department of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan. Electronic address: ashiuchi@kochi-u.ac.jp.
authors: Makoto
authors: M
authors: Ashiuchi
authors: Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors: Shota
authors: S
authors: Oike
authors: Research Center, Toyobo Co., Otsu, Shiga 520-0292, Japan.
authors: Hirofumi
authors: H
authors: Hakuba
authors: Research Center, Toyobo Co., Otsu, Shiga 520-0292, Japan.
authors: Shigeo
authors: S
authors: Shibatani
authors: Department of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors: Nogiho
authors: N
authors: Oka
authors: Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan; Department of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors: Taisuke
authors: T
authors: Wakamatsu
mesh_terms: D003124:Colorimetry / Q000379:methods; D005285:Fermentation; D018698:Glutamic Acid / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010968:Plasticizers / Q000032:analysis*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D045730:Soy Foods / Q000032:analysis*; D013025:Glycine max / Q000737:chemistry*; D013997:Time Factors
chemical_list: D010968:Plasticizers; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D018698:Glutamic Acid
keywords: Chiral HPLC; Colorimetric assay; Fermented soybeans; Plasticization; Poly-γ-glutamate