Amino Acids Nutritiono Evaluation Of Tartary Buckwheat Storge Protein SUbunites

Seed storage proteins of Tartary Buckwhea; are mainly compose of albumin and globulin with balanced amino acids nutrition and rich in semi-essential amino acid, such as arginine and histidine. Cloning genes coding related subunits is a feasible way to improve the protein nutrition of wheat and other crops through the genetic modifing approach. In this study, contents of total protein, albumin and globulin were measured by Kjeldahl and Bradford method. The subunits composition of proteins were analyzed by SDS-PAGE. Solubility, molecular weight, net charge differences and ethanol precipitation method explored to separate the proteins. The compositions of amino acids was derermined by amino acids analyzer, Protein fraction with high Ratio Coefficient of amino acid (SRCAA) were prepared and purified by SDS-PAGE and electroelution process, nutrition of separated subunits evaluated based on SRCAA according to FAO/WHO amino acids reference mode. Programme for the evaluation was designed by Perl language. The results indicated that:Total protein content in Tartary Buckwheat seed was 8.921%, albumin and globulin contents contribute to 24.7% and 14.6% of total protein separately, Electrophoresis results showed that the precipitated albumin using 40% ethanol had better effect to eliminate pigment contamination in the protein separation process.SDS-PAGE indicated that subunits of seed storage protein with polymorphism, albumin and globulin subunits dominated the middle and small molecular mass fraction.Fraction of albumin separated at 4℃and fraction of globulin separated under 0.25 mol/L salt concentration was further purified on DEAE Sephadex A-25 resin. Albumin and globulin were also separated by metal chelating chromatography. The precipination of albumin at 4℃and the globulin in 0.25 mol/L salt solution have high score of ratio coefficient of amino acids.Albumin precipitated in 4℃and globulin precipitated under 0.25mcl/L salt solution were analyzed by SDS-PAGE, and separated subunits were recovered by electioelution. Amino acids composition were analyzed and nutrition value were further evaluated. The results showed that all albumin and globulin subunits got relatively high score of ratio coefficient of amino acids (SRCAA) except subunits with molecular weight 27.5KDa and 22.4KDa, Albumin subunits with molecular weight 40.6Kda had highest SRCAA (71.76). Albumin subunit with 39.6KDa molecular weght got the score of 66.04. Globulin precipitated in 0.25mol/L salt solution with 36.6Kda subunit got balanced in amino acid with SRCAA 66.CO. Semi-essential coment of the three subunits were 155.2 mg/g,122.8 mg/g and 109.2 mg/g respectively, which was higher than corresponding component in egg protein.