Kinetic behavior of 25-hydroxyvitamin D-1-hydroxylase and -24-hydroxylase in rat kidney mitochondria.
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منابع مشابه
Kinetic behavior of 25-hydroxyvitamin D-1-hydroxylase and -24-hydroxylase in rat kidney mitochondria.
Although 25-hydroxyvitamin D (25-OHD)-l-hydroxylase and -24-hydroxylase have been measured extensively in fowl, no methods for assay of these enzymes have been validated for the mammal. Inhibitory activity present in all mammalian tissues is a hindrance to accurate measurement The mechanism by which protein components from rat tissues reduce chick 25OHDS-1-hydroxylase activity were studied by a...
متن کامل25-Hydroxyvitamin D3-24-hydroxylase in rat kidney mitochondria.
Assay conditions for the measurement of 25-hydroxyvitamin D3-24-hydroxylase activity in rat kidney mitochondria have been worked out. The product, 24,25-dihydroxyvitamin D3 was quantitated either by high pressure liquid chromatography or by isotope dilution-mass spectrometry. By these procedures, the enzyme activity could be measured with saturating concentration (greater than 2.5 X 10(-6) M) o...
متن کاملLocalization of 25-hydroxyvitamin D3 1 alpha-hydroxylase and 24-hydroxylase along the rat nephron.
Defined nephron segments were microdissected from the kidney of vitamin D-deficient rats, normal rats, and normal rats treated with 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25-(OH)2D3]. Tubule segments were incubated with 3H]labeled 25-hydroxyvitamin D3 and the rates of production of 3H]labeled 1 alpha, 25-(OH)2D3 and 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] were determined. Nephron segments ...
متن کاملMeasurement of mammalian 25 - hydroxyvitamin D 3 24 R - and la - hydroxylase ( 1 , 25 - dihydroxyvitamin D 3 / 24 , 25 - dihydroxyvitamin D / kidney / calcium ) YOKO TANAKA AND
An in vitro assay of mammalian 25-hydroxyvitamin D3 laand 24R-hydroxylases in kidney has been developed. It had been suggested that 25-hydroxyvitamin D binding protein present in mammalian blood and tissues inhibits the enzyme activities in cell-free preparations by binding the substrate 25-hydroxyvitamin D3 more strongly than the hydroxylases bind it. This inhibitory effect is overcome by the ...
متن کاملSmall-molecule inhibitors of 25-hydroxyvitamin D-24-hydroxylase (CYP24A1): synthesis and biological evaluation.
The synthesis of imidazole styrylbenzamide, tert-butyl styrylimidazole, and tert-butyl styrylsulfonate derivatives is described. Evaluation of binding affinity and inhibitory activity against CYP24A1 identified the imidazole styrylbenzamides as potent inhibitors of CYP24A1, having selectivity with respect to CYP27B1 comparable with or greater than that of the standard ketoconazole. Further eval...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1979
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(19)86336-6