Ethyl Tosyl-L-isoleucylg1ycinate.-A solution of tosyl-Lisoleucyl chloride (prepared from 2.9 g. of tosyl-L-isoleucine and-phosphorus pentachloride) in r5 ml. of anhydrous ether was added slowly to a suspension of 2.5 g. of ethyl glycinate hydrochloride and 3.5 ml. of triethylamine in 50 ml. of anhydrous ether and the mixture was allowed to stand at room temperature for 12 hours. The white precipitate was filtered off and washed with ether. After trituration with water to remove the triethylamine hydrochloride, 3.34 g. of product, m.p. 159-160°, was obtained; yield 89%. Another 0.25 g., m.p. 152-154', was afforded by extraction of the ether filtrate successively with water, dilute HCl, dilute aqueous KHCO, and water, followed by removal of the ether zn vacuo. Recrystallization of the second crop from ethanol raised the m.p. to 158-160". For analysis, the tosyl dipeptide ester was recrystallized twice from ethanol and then melted a t 160-161".

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Because the neurotoxic common vetch (Vicia sativa L.) legume seems to have come into some use in man's diet, we have investigated, using Pico-Tag analysis, the stability of the vetch neurotoxins to cooking. When heated in water at 100 °C for 3 h, γ-glutamyl-β-cyanoalanine (γ-gluBCA) cyclized extensively to form pyroglutamic acid and β-cyanoalanine (BCA). By contrast three specimens of common vetch seeds containing 0.42−0.74% γ-gluBCA and 0.01−0.03% BCA retained these principles without loss. A modified cooking procedure replacing the broth during cooking with fresh water and washing the seeds well yielded cooked seeds without detectable neurotoxins. A nutritional study confirmed that the toxins responsible for causing weight loss and mortality in chicks were removed. Lengthy steeping in water at room temperature also effectively removed the neurotoxins from dehulled split seeds but incompletely from intact seeds. These procedures improve the quality of common vetch seed as a source of protein for man. Keywords: Common vetch; Vicia sativa L.; legumes; nutrition; chicks; food toxins; detoxification; β-cyanoalanine; γ-glutamyl-β-cyanoalanine; pyroglutamic acid