BIOSYNTHESIS OF MUSTARD OIL GLUCOSIDES: VII. FORMATION OF SINIGRIN IN HORSERADISH FROM HOMOMETHIONINE-2-14C AND HOMOSERINE-2-14C

Five 14C-labeled amino acids were administered to horseradish (Armoracia lapathifolia Gilib.) leaves. Three of the amino acids, DL-homoserine-2-14C, DL-methionine-2-14C, and DL-homomethionine-2-14C (2-amino-5-(methylthio)-valeric acid), were precursors of the aglycone (allyl isothiocyanate) of sinigrin. The other two, DL-allylglycine-2-14C (2-amino-4-pentenoic acid) and DL-2-amino-5-hydroxyvaleric acid-2-14C, were incorporated in insignificant amounts. The relationships of the three efficient precursors are discussed. The syntheses of four 14C-labeled amino acids used in this investigation are described.