Non-protein nitrogenous constituents of rye grass: ionophoretic fractionation and isolation of a ‘bound amino-acid’ fraction

Abstract

A diaphragm-cell arrangement was adapted for the quantitative ionophoretic fractionation of plant juices by adding an extra compartment to the apparatus of Theorell and Akeson (1942). While it has been used here for separating N compounds, according to the net charges on their molecules it should also prove useful for separations of carbohydrates, mineral constituents, phosphoric esters, plant acids, etc. The ninhydrin-CO2 detn. was used for measuring free and "bound" alpha-amino acids in plant juices, and in this certain difficulties were encountered. The above technics, together with qualitative 2-dimensional filter-paper chromatography of amino acids, were used in studying those organic nitrogenous constituents of the juice of rye grass (Lolium perenne) which can diffuse through cellophane: The bulk of this non-protein N was made up by basic substances and by well known amino acids in the free state. Small quantities of bound amino acids were found in the form of basic and acidic compounds, but the greatest part of the bound amino acids, representing 4-10% of the diffusible non-protein N, was isolated ionophoretically in a fraction rich in carbohydrates but devoid of free amono acids. The material in this fraction seemed to be devoid of free amino or carboxyl groups, and on acid hydrolysis yielded ammonia, leucine and/or isoleucine, valine, proline, alanine, glycine, aspartic and glutamic acids. The present observations are discussed in relation to previous work on the free and bound amino acids of plant juices.