Effects of enzymatic deamidation by protein-glutaminase on structure and functional properties of wheat gluten.
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.
Yong
Yie Hui
YH
Laboratory of Quality Analysis and Assessment, Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Japan.
Yamaguchi
Shotaro
S
Matsumura
Yasuki
Y
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
D000485:Allergens; D045703:Emulsifying Agents; D014867:Water; D005983:Glutens; D005972:Glutaminase