On the mechanism of protein binding of N-2-fluorenylacetamide. The deacetylation of N-(1-hydroxy-2-fluorenyl)-acetamide and the effect of ethionine.

Homogenates of six rat tissues metabolized the o-amidofluorenol, N-(1-hydroxy-~fluorenyl)aeetamide, as judged by the disappearanee of the phenolic hydroxyl group of the compound from the ineubation systems. By the same criterion, N-(7-hydroxy-~fluorenyl)aeetamide was resistant to metabolie attack. The deaeylation of N-(1-hydroxy-~-fluorenyl)aeetamide, N-(7-hydroxy-~-fluorenyl)aeetamide, N-s and N-~-fluorenylaeetamide by twelve rat tissues was examined with the use of speetrophotometrie teehnies and radioaetive tracer methods. Only N-(1-hydroxy-~-fluorenyl)aeetamide was deaeetylated by all tissues. The aetion of 0.1 M potassium fluoride upon deaeetylation of N-(1-hydroxy-~fluorenyl)aeetamide-l-C TM and upon protein labeling by the radioactivity of N-~fluorenylaeetamide-9-C 14 was examined in rat liver homogenates; 0.1 M potassium fluoride inhibited deaeetylation as well as protein labeling. I t was eonfirmed in separate experiments tha t fluoride under these eonditions enhaneed hydroxylation as previously described. The data support a meehanism of protein binding of the eareinogen previously suggested on the basis of in vitro evidenee. This mechanism involves o-hydroxylation of N-~-fluorenylaeetamide followed by deaeetylation and subsequent oxidation of the resulting o-aminophenol to the o-quinoneimine which in turn may combine with protein. The role of the inhibition of protein synthesis by DL-ethionine upon the binding of N~-fluorenylaeetamide-9-C TM was tested. No effect of this antimetabolite upon binding was observed.