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The Action of the Carcinogen N-(2-Fluorenyl)acetamide on Rat Liver Catalase and Arginase in Vivo^*

C. M. King and H. R. Gutmann

( Laboratory for Cancer Research, Veterans Administration Hospital, and the Department of Biochemistry, University Minnesota Medical School, Minneapolis)

The oral administration of the carcinogens N-(2-fluorenyl)acetamide and N-hydroxy-2-fluorenylacetamide to male rats for 6 weeks depressed the activity of liver catalase to the extent of 20–25 per cent, but had no effect on liver arginase. The catalase activity was restored by withdrawal of the compounds from the diet. The administration of the noncarcinogenic metabolite N-(1-hydroxy-2-fluorenyl)acetamide had no effect on the activity of either liver catalase or arginase. Catalase isolated from rat liver after the intraperitoneal administration of carbon-14-labeled N-(2-fluorenyl)acetamide or N-(1-hydroxy-2-fluorenyl)acetamide contained only negligible quantities of bound C¹⁴. The evidence supports the view that the covalent binding of N-(2-fluorenyl)acetamide or of one of its metabolites is not a probable mechanism for the inhibition of catalase in vivo. Determinations of the total iron content of the liver after the feeding of N-(2-fluorenyl)acetamide gave no indication that a disturbance of the over-all iron metabolism was implicated in the lowering of the catalase activity. Since oral feeding of N-(2-fluorenyl)acetamide or N-hydroxy-2-fluorenylacetamide, but not of N-(1-hydroxy-2-fluorenyl)acetamide, decreased the protein content of the liver, it is suggested that the partial inactivation of catalase in vivo is due to a selective action of these carcinogens on enzyme synthesis or destruction.

^* Supported by grant C-2571, National Cancer Institute, U. S. Public Health Service.

The authors thank Frank A. Puglisi and May V. Collin for technical assistance.

Present address: Department of Biochemistry, Netherlands Cancer Institute, Amsterdam.

To whom inquiries regarding this article should be sent.

Received 11/ 2/63.