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.

Shear, heat and pH induced conformational changes of wheat gluten – Impact on antigenicity

“…3). Second derivative of amide I region (1600-1700 cm À1 ) of the spectrum was investigated and the peaks at 1620 and 1630 cm-1 (b sheet), 1650 cm-1 (a helix), 1666 cm-1 (b turn structure) and 1680 cm-1 (intramolecular b sheet) (Yong, Yamaguchi, & Matsumura, 2006) were evident (Fig. 2).…”

Modifications of structures and functions of caseins: a scientific and technological challenge

“…This enzyme was discovered in the culture supernatant of Chryseobacterium proteolyticum (Yamaguchi and Yokoe 2000;Yamaguchi et al 2001), and its action was investigated on several food proteins Gu et al 2001;De Jong and Koppelman 2002;Yong et al 2004Yong et al , 2006. On skim milk proteins, Miwa et al (2010) showed that deamidation increased the electronegativity of caseins due to the formation of supplementary carboxyl groups leading to a reduction of the pHi toward lower pH.…”

Gene Cloning, Purification, and Characterization of a Novel Peptidoglutaminase-Asparaginase from Aspergillus sojae

“…Although the deamidation of proteins can be performed either enzymatically or nonenzymatically (i.e., chemically), enzymatic protein modification has several advantages over chemical treatment, such as milder reaction conditions, increased reaction rate, and higher specificity. Specifically, transglutaminase, protease, peptidoglutaminase, and protein-glutaminase enzymes have been shown to catalyze protein deamidation (5,6,26,34).Soy sauce is a traditional Japanese seasoning that is manufactured by fermenting steamed soybeans and roasted wheat with koji molds (Aspergillus sojae or Aspergillus oryzae) along with water and salt. A. sojae is preferentially used to make soy sauce due to its high proteolytic activity.…”