Characterization of proteins in Cuphea (PSR23) seeds

This study characterized the proteins in Cuphea (PSR23) seed to provide fundamental information on their size, amino acid profile, solubility classes, and solubility behavior. The seed contained 32% (dry basis, db) oil and 21 % (db) crude protein. Over 70% of the protein was extracted at pH 11.6. Nonprotein nitrogen accounted for 9% of the total N content. Compared with the Food and Agriculture Organization/World Health Organization/United Nations University suggested pattern of requirements, Cuphea PSR23 seed protein had sufficient amounts of methionine + cystine-cysteine, considerable amounts (90%) of valine, phenylalanine + tyrosine, but was practically devoid of tryptophan. Lysine was the second-most limiting essential amino acid at 68%. Glutelins and albumins accounted for 83.5 and 15.4%, respectively, of the total protein extracted. SDS-PAGE showed that Cuphea protein subunits had M.W. ranging from < 6.5 to 110 kDa. Dominant protein subunits in albumins had M.W. of 30, 40, 50, and 86 kDa. Glutelins had two major protein subunits with M.W. of 15 and 30 kDa. The distribution of essential amino acids was better in the albumin and glutelin fractions than in the defatted meal.