Isolated rat hepatocytes incubated with two suicide substrates of cytochrome P-450, 2-allyl-2-isopropylacetamide and 3,5-diethoxycarbonyl-4-ethyl-1,4-dihydro-2,6-dimethylpyridine(4-ethyl-DD C), convert exogenous mesohaem and deuterohaem into N-alkylated mesoporphyrins and deuteroporphyrins respectively. The N-alkylated mesoporphyrins can be separated by h.p.l.c. from the corresponding N-alkylated protoporphyrins originating from endogenous haem; in this way the contribution of both endogenous and exogenous pools of haem can be studied in the same experiment. N-Alkylated mesoporphyrin exhibits chiral properties, and its isomeric composition and/or amount are dependent on the particular cytochrome P-450 enzyme predominating in the cell. These findings provide additional and more direct evidence that exchangeable haem is taken up by cytochrome P-450 before being N-alkylated.
N-alkylation of exogenous haem analogues caused by drugs in isolated hepatocytes. Structural isomerism and chirality of the resulting porphyrins
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F De Matteis, C Harvey, S R Martin; N-alkylation of exogenous haem analogues caused by drugs in isolated hepatocytes. Structural isomerism and chirality of the resulting porphyrins. Biochem J 15 August 1986; 238 (1): 263–268. doi: https://doi.org/10.1042/bj2380263
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