The metabolism of the carcinogen N-(2-fluorenyl) acetamide by liver cell fractions.

In previous communications from this laboratory we have reported that the hydroxylation of the carcinogen N-(2-fluorenyl)acetamide can be readily demonstrated in slices (1, 2) and in homogenates fortified with diphosphopyridine nucleotide and succinate (3), but not in unfortified homogenates (1, 3). It was also found that the binding of the radioactivity of N-(Zfluorenyl) acetamide-g-C*4 to cellular proteins occurred only at a very low level in unfortified homogenates, but was increased several-fold when diphosphopyridine nucleotide and succinate were added (2, 3). These data suggested a relation between hydroxylation of N-(2-fluorenyl)acetamide and protein binding. Protein binding is currently considered to play a part in the action of chemical carcinogens and may be required for the induction of neoplasms by chemical agents (4). Since hydroxylation of N(2-fluorenyl)acetamide seemed implicated in this reaction, a further characterization of the enzymatic system(s) concerned with the hydrosylation and concurrent deacetylation of N-(2fluorenyl)acetamide appeared desirable. The present report deals with the optimal conditions for the hydrosylation of N-(2-fluorenyl)acetamide and the role of triphosphopyridine nucleotide or diphosphopyridine nucleotide in this reaction. The intracellular distribution of the hydrosylating and deacetylating systems has been defined, and the effects of a number of enzyme inhibitors upon the hydroxylating and deacetylating activities have been examined. The abilities of different species to hydroxylate the carcinogen have been compared. Finally, several hydrosylated metabolites of N-(2-fluorenyl) acetamide have been identified by paper chromatography after incubation of liver cell fractions with the compound.