Fractionation of plant material. IV.—Distribution of amino acid residues in fractions obtained from leaves of broad bean (Vicia faba L.)

The quantitative distribution of amino-acid residues amongst some fractions derived from broad-bean leaves was determined. Among the free amino acids, asparagine predominated and 3,4-dihydroxyphenylalanine (DOPA) was abundant. DOPA was absent from the protein fractions. Aggregated N recovery and amino acid composition resembled those found for leafy materials by previous workers. Material extracted by ethanol from the TCA-precipitated fraction resembled the bulk protein in molecular size and amino acid composition. A fraction not migrating during electrophoresis in phenol-acetic acid-water gave, on hydrolysis, amino acids presumed to be bound in neutral or weakly acid compounds, mostly of low molecular weight.