La degradation de la L-lysine chez le ra “germ-free”

Abstract L - Lysine degradation in the ‘germ-free’ rat The fate of uniformly 14 C-labelled L -lysine (I), δ 1 -piperideine-2-carbpxylic acid (II) and uniformly 14 C-labelled L -pipecolic acid (III) in intact ‘germ-free’ rats has been explored. The fraction of initial radioactivity recovered in respiratory CO 2 within the first 6 h amounts to 10% for I, 0.6% for II and less than 0.1% for III. Pipicolic acid is excreted unchanged in the urine, and it was impossible to detect the presence of α-aminoadipic or piperidone-carboxylic acid. These results are compared with those of other authors and discussed. It seems to be well estbalished that pipecolic acid is, in fact, not metabolized by the germ-free rat; it is not on the major α-aminoadipic acid pathway of lysine degradation, but on a side path.