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Characterization of a high molecular weight flaxseed protein |
R. EL-RAMAHI1, I. Alli1, Y. Konishi2, S. Kermasha1, and F. Yeboah2. (1) Dept. of Food Science & Agricultural Chemistry, McGill Univ., Macdonald Campus, 21111 Lakeshore Rd., Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada, (2) Biotechnology Research Institute, National Research Council of Canada, Pharmaceutical Biotechnology Sector, 6100 Royalmount Ave., Montreal, QC H4P 2R2, Canada Proteins from plant sources continue to be of interest to certain sectors of the food industry. Estimates indicate that world plant protein consumption is 170 million tons per year with soybean as the most popular source. Flaxseed contains approximately 20% protein. It is used predominantly as a source of oil for industrial applications leaving a high-protein residual meal. The nutritional attributes of flaxseed and in particular, recently identified nutraceutical compounds such as lignans, make the meal a potential source of edible protein. At present, there is limited published information on the structural and functional properties of flaxseed proteins; it is essential to obtain a more complete understanding of these properties with a view of their use in foods. The aim of this project was to isolate and characterize a major protein extracted from defatted flaxseed meal. In our study, the major flaxseed protein was prepared by a sodium hydroxide (NaOH) extraction followed by isoelectric precipitation. The protein was subjected to reverse-phase high performance liquid chromatography (RP-HPLC) and fractions were identified by electrophoresis; they were then analyzed by electro-spray ionization mass spectrometry (ESI-MS) for molecular weight determination. The yield from NaOH extraction and isoelectric precipitation was 24.1%; the protein content was 67.15% (N X 6.25). Native polyacrylamide gel electrophoresis indicated that the molecular weight of the protein was 320KDa; SDS-PAGE showed that the protein comprised of 5 subunits ranging from 10,250 to 36,000Da. SDS-PAGE under reducing conditions with b-mercaptoethanol gave similar results when compared to SDS-PAGE under non-reducing conditions. RP-HPLC separated the protein into 3 fractions, which gave molecular weights ranging from 5,890 to 42,540Da by ESI-MS. A major protein fraction in flaxseed was obtained and its subunits were identified by SDS-PAGE and ESI-MS. These subunits have not been reported previously.
Session 11, Food Chemistry: Proteins I
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