The formation in vivo of lombricine in the earthworm (Megascolides cameroni)

Abstract

When [1,2C214] ethanolamine, DL-[3-C14]-serine, L-[H3]serine or D-[Sr]serine was administered orally to earthworms, serine ethanolamine phosphodiester and lombricine were found to be radioactively labeled. In each instance the specific radioactivity of serine ethanolamine phosphodiester was greater than that of lombricine both in muscle and in gut tissue and greater in gut than in muscle. With [1,2-C2 ] ethanolamine most of the radioactivity of muscle lombricine was in the guanidinoethanol portion of the molecule, whereas with DL-[3-C14J serine most of it was in the serine portion. When L-[amidino-C14] arginine was given, there was negligible radioactivity in serine ethanolamine phosphodiester and considerable radioactivity in lombricine, almost all of which was in the guanidinoethanol portion of the molecule. These findings suggest that serine ethanolamine phosphodiester is the precursor of lombricine in the earthworm and that the amidino group is derived from arginine by the transamidinase catalyzed transfer of the amidino group to serine ethanolamine phosphodiester.