1. Changes in certain kinetic properties (Vmax. and apparent Km) of hepatic microsomal mixed-function oxidases have been studied as a function of postnatal development and maturation in male rats. 2. Microsomal cytochrome P-450 content changed only slightly between 1 and 12 weeks of age. 3. Aniline hydroxylase activity (Vmax.) increased abruptly between 1 and 2 weeks of age to greater than adult activities and then returned to a plateau value between 4½ and 12 weeks of age. Ethylmorphine demethylase activity remained low and relatively constant between 1 and 3 weeks of age and then increased markedly (∼100%) between 3 and 4½ weeks. 4. The apparent Michaelis constant (Km) for aniline hydroxylation increased almost linearly with time between 1 and 6 weeks of age and tended to reach a plateau value thereafter. The apparent Km for ethylmorphine demethylation increased between 1 and 3 weeks of age and then decreased abruptly to a constant value between 6 and 12 weeks. 5. The data indicate that developmental changes in the activity of these microsomal oxidases do not correlate temporally with each other or with changes in microsomal cytochrome P-450 content. 6. The most dramatic changes in enzyme activity were associated with early development (1–3 weeks) and weaning (3–4 weeks). 7. Changes in weight of seminal vesicle, a criterion of sexual maturation in male rats, were most prominent between 6 and 8 weeks of age and thus appeared to be separated in time from the prominent changes in enzyme activity.
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July 1969
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Research Article|
July 01 1969
Changes in certain kinetic properties of hepatic microsomal aniline hydroxylase and ethylmorphine demethylase associated with postnatal development and maturation in male rats
Theodore E. Gram;
Theodore E. Gram
1Laboratories of Chemical Pharmacology, National Heart Institute and National Cancer Institute, National Institutes of Health, Bethesda, Md. 20014, U.S.A.
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Anthony M. Guarino;
Anthony M. Guarino
1Laboratories of Chemical Pharmacology, National Heart Institute and National Cancer Institute, National Institutes of Health, Bethesda, Md. 20014, U.S.A.
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David H. Schroeder;
David H. Schroeder
1Laboratories of Chemical Pharmacology, National Heart Institute and National Cancer Institute, National Institutes of Health, Bethesda, Md. 20014, U.S.A.
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James R. Gillette
James R. Gillette
1Laboratories of Chemical Pharmacology, National Heart Institute and National Cancer Institute, National Institutes of Health, Bethesda, Md. 20014, U.S.A.
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Publisher: Portland Press Ltd
© 1969 The Biochemical Society
1969
Biochem J (1969) 113 (4): 681–685.
Citation
Theodore E. Gram, Anthony M. Guarino, David H. Schroeder, James R. Gillette; Changes in certain kinetic properties of hepatic microsomal aniline hydroxylase and ethylmorphine demethylase associated with postnatal development and maturation in male rats. Biochem J 1 July 1969; 113 (4): 681–685. doi: https://doi.org/10.1042/bj1130681
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