Exposure of cultured chick-embryo hepatocytes to increasing concentrations of CoCl2 in the presence of allylisopropylacetamide results in formation of cobalt protoporphyrin, with a reciprocal decrease in haem and cytochrome P-450. Treatment of rats with CoCl2 (84 mumol/kg) and 5-aminolaevulinate (0.2 mmol/kg) also results in formation of cobalt protoporphyrin and a decrease in cytochrome P-450 in the liver. Hepatic microsomal fractions from rats treated with phenobarbital, CoCl2 and 5-aminolaevulinate were analysed by polyacrylamide gel electrophoresis. Cobalt protoporphyrin was associated mainly with proteins of 50000-53000 mol.wt. The results suggest that the formation of cobalt protoporphyrin occurred at the expense of the synthesis of haem, leading to a decrease in cytochrome P-450. Furthermore, the cobalt protoporphyrin that was formed may itself have been incorporated into apocytochrome P-450.
Decrease in hepatic cytochrome P-450 by cobalt. Evidence for a role of cobalt protoporphyrin
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J F Sinclair, P R Sinclair, J F Healey, E L Smith, H L Bonkowsky; Decrease in hepatic cytochrome P-450 by cobalt. Evidence for a role of cobalt protoporphyrin. Biochem J 15 April 1982; 204 (1): 103–109. doi: https://doi.org/10.1042/bj2040103
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