ISOLATION OF AMINO ACIDS FROM PISUM SATIVUM . IDENTIFICATION OF L(-)-HOMOSERINE AND L(+)-O-ACETYLHOMOSERINE AND CERTAIN EFFECTS OF ENVIRONMENT UPON THEIR FORMATION

l-aspartic acid, l-glutamic acid, γ-aminobutyric acid, l-alanine, l-valine and l-leucine were isolated from pea plants, crystallized and their identity established by comparison with authentic substances, and by analysis. Especial attention was also given to two others, l-homoserine and l-O-acetylhomoserine, which were also isolated in a pure state. The properties which confirm the occurrence of l-(-)-homoserine and the evidence which critically establishes the identity of l(+)-O-acetylhomoserine are described. Whereas l-homoserine and l-O-acetylhomoserine exist as though they were in dynamic equilibrium in the pea plants, asparagine behaves differently. This is shown by the effects of growth (during 77 days) at different night temperatures, from 4 to 26°, under 16-hr nights on the amino acid composition of pea shoots. The lower the night temperature, the higher was the concentration of homoserine and O-acetylhomoserine, but the night temperature had the opposite effect on asparagine. The significance of these results is discussed. © 1969.