Protein-bound Dye and Purine-catabolyzing Enzymes in Parenchymal and Nonparenchymal Cells of Rats Fed 4-dimethylaminoazobenzene.

The binding of 4-dimethylaminoazobenzene to proteins and the enzymatic activities of some purine-catabolyzing enzymes during feeding of the carcinogen have been in vestigated by analysis of two liver fractions differing in their cytological composition. At an early stage of feeding dye binding occurred at a faster rate in nonparenchymal cells than in parenchymal cells. Binding in nonparenchymal cells reached a maximum after 1 week of feeding and decreased afterward, whereas maximum binding in the parenchymal cells was observed after 4 weeks. The decrease in the amount of bound dye in parenchymal cell that followed was accompanied by a second peak in nonparen chymal cells. The results on the activities of the purine-catabolyzing enzymes show that a de crease in 5'-nucleotidase, inosine phosphorylase, and uricase activities occurred in