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. 1978 Jun 15;172(3):417-22.
doi: 10.1042/bj1720417.

Kinetics of liver microsomal cholecalciferol 25-hydroxylase in vitamin D-depleted and -repleated rats

E E Delvin, A Arabian, F H Glorieux

Kinetics of liver microsomal cholecalciferol 25-hydroxylase in vitamin D-depleted and -repleated rats

E E Delvin et al. Biochem J. .

Abstract

Kinetics of vitamin D-depleted and -repleted rat liver microsomal cholecalciferol 25-hydroxylase were studied. Anaerobiosis, CO, omission of a NADPH-generating system and addition of detergents all decreased the activities, showing that the hydroxylase behaves like a cytochrome P-450-dependent enzyme. An apparent Km of 0.18 micrometer and Vmax. of 32pmol/min per g of tissue were found for vitamin D-deficient animals. Although both apparent Km and Vmax. were significantly altered in vitamin D-repleted animals no inhibition of the enzyme was elicited. These latter results show that at normal vitamin D intake, rat liver cholecalciferol 25-hydroxylase is not feedback-inhibited.

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References

    1. Cancer Res. 1957 Jul;17(6):628-33 - PubMed
    1. Biochem Biophys Res Commun. 1963 Aug 14;12:388-94 - PubMed
    1. J Lipid Res. 1975 Nov;16(6):448-53 - PubMed
    1. J Clin Invest. 1976 Apr;57(4):897-903 - PubMed
    1. Annu Rev Biochem. 1976;45:631-66 - PubMed