title: Effects of enzymatic deamidation by protein-glutaminase on structure and functional properties of wheat gluten.
abstract: Protein-glutaminase (PG) purified from Chryseobacterium proteolyticum was used to investigate its deamidation effects on wheat gluten. Water-insoluble gluten was able to be deamidated to the extent of deamidation degree (DD) 72% in 200 mM sodium phosphate buffer (pH 7) at 40 degrees C for 30 h. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis exhibited an upper shift of gluten bands with only deamidation for 1.5-2.0 h (DD 35-45%) compared to the bands of nondeamidated gluten. Results of Fourier transform infrared analysis revealed alterations in secondary structure of gluten by PG deamidation. The assignment within amide I region showed decreases in both inter- (around 1695 cm(-1)) and intramolecular beta-sheets (around 1680 cm(-1)) by deamidation suggesting the deterioration of the aggregation ability of gluten molecules. Solubility and emulsification properties of gluten at pH 7 were improved by deamidation, while both properties at pH 3 were deteriorated by deamidation. Enzyme-linked immunosorbent assay identified that allergenicity of deamidated gluten as compared to the nondeamidated cohorts was decreased remarkably as the deamidation time was prolonged.
authors.affiliation: Laboratory of Quality Analysis and Assessment, Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Japan.
authors.forename: Yie Hui
authors.initials: YH
authors.lastname: Yong
authors.forename: Shotaro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Matsumura
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D045703:Emulsifying Agents / Q000737:chemistry; D005972:Glutaminase / Q000378:metabolism*; D005983:Glutens / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017433:Protein Structure, Secondary; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D014908:Triticum / Q000737:chemistry*; D014867:Water
chemical_list: D000485:Allergens; D045703:Emulsifying Agents; D014867:Water; D005983:Glutens; D005972:Glutaminase