Low molecular weight seed proteins are restricted to the embryo
part of the buckwheat grain where low M.W. proteins cannot
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part of the buckwheat grain where low M.W. proteins cannot be detected. 2. Results and discussion Buckwheat seed proteins extracted from endosperm and embryo were analyzed by SDS-PAGE electrophoresis. Six intense bands were detected from buckwheat endosperm extracts ( Fig. 1 ). Two most intense bands were in the range of M.W.s from 50 to 60 kDa. These proteins have been shown not to be associated with allergy [29,30] . In contrast, no low weight protein bands were detected in the range from 6.5 to 29 kDa on the electropherogram of buckwheat endosperm extracts. The most active proteins causing buckwheat allergy have been clearly connected with the abundant legumin-type buckwheat grain proteins, with M.W.s ranging from 18 to 29 kDa [31,32,36,37] . These protein bands are shown here to be associated exclusively with buckwheat embryo. Milisavljevic´ et al. [38] showed that antibodies made against 23–25 kDa polypeptides did not cross-react with the 57 kDa polypeptide, which is a subunit of 8S globulin (the main buckwheat storage protein) and is one of the six intense bands that we detected on the electropherogram of buck- wheat endosperm protein extract. This finding is in agree- ment with the reports of Urisu et al. [29] and Nair and Adachi [30] that the 57 kDa polypeptide was not recognized by sera from allergic patients. Maruyama-Funatsuki et al. [39] found some differences in the BW24KD protein content between different cultivars and within cultivars of buckwheat, although no plants were found to lack BW24KD. Skrabanja et al. [16] separated different milling fractions, by a combination of sieving and repeated milling, into 23 frac- tions (seven fine flours, three coarse flours, four small semo- lina fractions, two large semolina fractions, six bran frac- tions and one husk fraction). In these fractions there were different amounts of crude protein and starch. Components responsible for technological properties may also be concen- trated or regulated to obtain the desired end-use product. Simi- larly, depending on the metabolic or physiological need of a patient, the appropriate fraction may be chosen to achieve the desired effect [16] . The results presented here lead to the pro- posal that patients with hypersensitivity to buckwheat flour should use only fine flour from buckwheat endosperm, as this fraction contains no or very few low M.W. seed proteins. In this study we have demonstrated that buckwheat seeds can be separated into husk, embryo and endosperm. No low Fig. 1 . Electropherogram of common buckwheat endosperm (E) and embryo (C); S–Wide range molecular markers. The most intensive protein bands on endosperm electropherograms range from 36 to 205 kDa. No protein bands on endosperm electropherograms were detected in the range from 6.5 to 36 kDa. 863 M. Licˇen, I. Kreft / Plant Physiology and Biochemistry 43 (2005) 862–865 M.W. proteins could be detected on electropherograms of buckwheat endosperm. There appeared a tissue specific pres- ence of proteins of different size classes of the endosperm and embryo tissues. Protein of 57 kDa has been shown not to cross-react against antibodies raised against proteins of M.W. ranging between 23 and 25 kDa [29,30,38] . There are no reports about the allergenicity of other endosperm proteins. There are no reports about the allergenicity of other en- dosperm proteins. It seems that endosperm cells because of their high specialization contain very low amount of low M.W. proteins, including small housekeeping proteins. With im- proved technology it should be possible to separate endosperm from embryo on the larger scale, which would enable prod- ucts to be made from buckwheat flour that could be more appropriate for patients with hypersensitivity to buckwheat flour than buckwheat flour products generally used. tải về 109.87 Kb. Chia sẻ với bạn bè của bạn:
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