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Aminopyrine N ‐demethylase activity in human liver microsomes
Author(s) -
GarcíaAgúndez Jose Augusto,
Luengo Antonio,
Benítez Julio
Publication year - 1990
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1990.184
Subject(s) - microsome , cytochrome b5 , cytochrome , demethylase , reductase , chemistry , enzyme , specific activity , population , cytochrome p450 , michaelis–menten kinetics , biochemistry , medicine , endocrinology , enzyme assay , biology , epigenetics , environmental health , gene
Aminopyrine N ‐demethylase activity and the contents of cytochrome P‐450, cytochrome b 5 , and NADPH‐reductase activity in human liver microsomes from 31 different patients were studied. Our results show the existence of significant interindividual, but not sex‐ or age‐related differences N ‐demethylase activity (ranging between 0.52 and 4.42 nmol/min/mg protein), and that these differences are directly correlated with the content of cytochrome P‐450 and NADPH‐reductase activity, but not with that of cytochrome b 5 content, in the samples. In contrast, no differences were found in the Michaelis‐Menten constant values for aminopyrine (mean, 2.4 mmol/L) or NADPH (mean, 69 μmol/L), strongly suggesting that interindividual differences could be due to the occurrence of different amounts of the same enzyme, rather than the presence of different enzymes, in the population studied. Clinical Pharmacology and Therapeutics (1990) 48, 490–495; doi: 10.1038/clpt.1990.184