Fractionation and characterization of the alcohol-soluble proteins of a barley variety, its mutants, and Hiproly, a high-protein and high-nutritive barley isolated from the world barley collection, indicate quantitative and qualitative changes in the mutants. The 35 % ethanol-soluble subfraction is higher in proportion in the mutants and Hiproly, and this could have resulted from the higher proportions of the polar amino acids in these proteins among which are also some limiting amino acids like lysine and threonine. The digestibility, as observed by the in vitro procedure, of this subfraction in all the varieties also is higher and, presumably as a result, the hordein fraction of these mutants also shows better digestibility. It appears that, in view of the presence of more polar amino acids which include lysine in this subfraction and better digestibility, its enrichment could be a nutritionally favorable index of better grain quality.
The absorption at 360 me shown by 2,4-dinitrophenyl-amino acids in aqueous solution is very sensitive to changes in hydrogen ion concentration in the pH range 1 to 5. Twenty-one 2,4-dinitrophenyl derivatives have been examined for changes in absorbancy at 360 me at various hydrogen ion concentrations, and the approximate pK of the car-
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