title: Decreased activity of uroporphyrinogen decarboxylase caused by 2,4,5,3',4'-pentabromobiphenyl in chick embryo hepatocyte cultures. Difference in activity in intact or homogenized cells.
abstract: Uroporphyrinogen decarboxylase activity was investigated in cultures of chick embryo liver by two different methods: (1) analysis of porphyrin composition following incubation of intact cells with delta-aminolevulinic acid; and (2) a more conventional direct enzymic assay of cell homogenates. Activity was detectibly decreased following exposure of cells to 100 ng/ml 2,4,5,3',4'-pentabromobiphenyl using the first method, but not the second. This decrease in activity was reversed by homogenizing the cells treated with 100 ng/ml pentabromobiphenyl. It is concluded that the direct homogenate assay of the enzyme may miss or underestimate decreases in its in vivo activity.
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology*; D002262:Carboxy-Lyases / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D011075:Polybrominated Biphenyls / Q000494:pharmacology*; D011166:Porphyrins / Q000378:metabolism; D014575:Uroporphyrinogen Decarboxylase / Q000378:metabolism*
chemical_list: D001713:Biphenyl Compounds; D011075:Polybrominated Biphenyls; D011166:Porphyrins; D000622:Aminolevulinic Acid; D002262:Carboxy-Lyases; D014575:Uroporphyrinogen Decarboxylase; C035354:2,4,5,3',4'-pentabromobiphenyl