Gliadins represent alcohol-soluble fraction of wheat storage proteins which is responsible for development of celiac disease. The only and effective treatment for celiac disease is strict adherence to a gluten-free diet excluding any food made with wheat, as well as rye, barley and possibly oat flour. Enzymatic modification of wheat gliadins seems to be an alternative method for decreasing of celiac activity. The aim of our study was a trial of enzymatic modification of wheat gliadins using fungal (Aspergillus sp., Aspergillus oryzae, Aspergillus niger) and bacterial (Bacillus licheniformis, Bacillus stearothermophilus, Bacillus thermoproteolyticus, Streptomyces griseus) proteases. The reaction was performed up to 60 min, stopped by addition of appropriate synthetic inhibitor and products of limited proteolysis were analyzed by SDS-PAGE method. From fungal proteases most effective proteolytic activity was observed using acid proteinase from A. niger since wheat gliadins and low molecular weight peptides were completely degraded. Bacterial proteases form B. licheniformis and B. thermoproteolyticus acted very effective and as the result of hydrolysis, the products of lower molecular weight (
Chia seed (Salvia hispanica L.) is an annual herbaceous plant categorized under Lamiaceae family. Chia seeds were investigated as a source of proteins and natural antioxidants. It is a potential alternative source of high quality protein, fats, carbohydrates, high dietary fibre, vitamins and mineral elements. The objective of this study was to evaluate chia seed from protein content and antioxidant acivity and highlight the quality of this pseudocereal. A crude protein, moisture content, content of protein fractions, total antioxidant capacity (TAC) and superoxide dismutase activity of chia seeds and food products containing chia seeds were determined. The protein content of chia seeds ranged from 2.9% to 4.6% dry matter from that albumins and globulins ranged from 54.6% to 62.8%. Chia is poor in a prolamines (<15%). Various chia seeds showed differences in their SOD activity and exhibited the high antiradical activity against 2,2-azino-bis(3ethylbenzothiazoline-6-sulphonic acid) (ABTS). The highest antioxidant capacity was found in sample chia seeds from Bolivia (1.46 mM TEAC.g -1 in the dry matter) and the lowest values of antioxidant activity was estimated in sample chia seeds from Argentina (1.05 mM TEAC.g -1 in the dry matter). The highest SOD activity was determined in sample chia from Argentina (2191.8 U.g -1 in the dry matter). The lowest SOD activity was found in sample chia-bio from Argentina (754.0 U.g -1 in the dry matter.). It makes them potentially suitable for use in the gluten-free diet of coeliac people and it can be used as a potential ingredient in health food because of its high antioxidant activity.
The identification and quantification of cereal storage proteins is of interest of many researchers. Their structural or functional properties are usually affected by the way how they are extracted. The efficiency of extraction process depends on the cereal source and working conditions. Here, we described various commonly used extraction protocols differing in the extraction conditions (pre-extraction of albumins/globulins, sequential extraction of individual protein fractions or co-extraction of gluten proteins, heating or non-heating, reducing or non-reducing conditions). The total protein content of all fractions extracted from commercially available wheat and rye flours was measured by the Bradford method. Tris-Tricine SDS-PAGE was used to determine the molecular weights of wheat gliadins, rye secalins and high-molecular weight glutelins which are the main triggering factors causing celiac disease. Moreover, we were able to distinguish individual subunits (α/β-, γ-, ω-gliadins and 40k-γ-, 75k-γ-, ω-secalins) of wheat/rye prolamins. Generally, modified extraction protocols against classical Osborne procedure were more effective and yields higher protein content in all protein fractions. Bradford measurement led into underestimation of results in three extraction procedures, while all protein fractions were clearly identified on SDS-PAGE gels. Co-extraction of gluten proteins resulted in appearance of both, low-molecular weight fractions (wheat gliadins and rye secalins) as well as high-molecular weight glutelins which means that is not necessary to extract gluten proteins separately. The two of three extraction protocols showed high technical reproducibility with coefficient of variation less than 20%. Carefully optimized extraction protocol can be advantageous for further analyses of cereal prolamins.
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