TOXIC PRINCIPLE IN VETCH . ISOLATION AND IDENTIFICATION OF GAMMA-L-GLUTAMYL-L-BETA-CYANOALANINE FROM COMMON VETCH SEEDS . DISTRIBUTION IN SOME LEGUMES

γ-Glutamyl-β-cyanoalanine has been identified in seedlings and seeds of common vetch and isolated from the seeds in crystalline form after electrophoresis or anion-exchange chromatography. Its structure has been confirmed by synthesis. For this a mixed anhydride procedure and protecting groups that were removed by hydrogenolysis were used. The α isomer, α-glutamyl-β-cyanoalanine, also has been synthesized and differs in its properties from the naturally occurring peptide. 7-Glutamyl-/3-cyanoalanine is neurotoxic to the young rat and chick. Together with the β-cyanoalanine present in the free state, it can account for the toxicity of common vetch seeds to the chick. Among seeds of 41 various legumes that have been surveyed quantitatively, β-cyanoalanine is present in every variety of common vetch and in approximately one-third of the vetch species and is accompanied by β-cyanoalanine in bound form. © 1969, American Chemical Society. All rights reserved.