Biosynthesis of the Piperidine Nucleus The mode of incorporation of lysine into pipecolic acid and into piperidine alkaloids

6-3H,6-14C-DL-Lysine was administered in “metabolite overloading” experiments to the intact rat, to a lysine-less mutant of Neurospora crassa, to intact bean plants (Phaseolus vulgaris), and to excised shoots of Sedum acre. Pipecolic acid was then isolated from the tissues. In each case the pipecolic acid showed a 3H:14C ratio which was similar to that of the administered precursor. It follows that, in each case, the conversion of lysine into …