[Vergleichende Untersuchungen mit (14c)5-Aminolävulinat und (14c)Uroporphyrinogen (author's transl)].

Cell-free extracts from Clostridium tetanomorphum, a microorganism which synthesizes corrins but no heme, are capable of converting both 5-aminolevulinate and uroporphyrinogen III into cobyrinic acid. Comparative examinations with (14C)5-aminolevulinate and (14C)uroporphyrinogen yielded corresponding results. Cell-free extracts from Clostridium tetanomorphum contain uroporphyrinogen III. To obtain good radiochemical yields it is therefore necessary to use substrates of high specific radioactivity. A method for the preparation of 14C-labelled uroporphyrin I-IV with high specific radioactivity is described.