Abstract
An in vitro assay of mammalian 25-hydroxyvitamin D3 1 alpha- and 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 addition of substantial amounts of unlabeled 25-hydroxyvitamin D3 to saturate the binding sites of this protein. The resulting metabolites produced in vitro by rat kidney homogenates were isolated and firmly identified by ultraviolet absorption spectrometry and mass spectrometry as 1,25-dihydroxyvitamin D3 and (24R)-24,25-dihydroxyvitamin D3. Maximal 1 alpha-hydroxylation of 25-hydroxyvitamin D3 could be demonstrated in kidney homogenates prepared from vitamin D-deficient rats. Thyroparathyroidectomy of these rats resulted in total suppression of the 1 alpha-hydroxylase. Homogenates of kidney from rats given vitamin D showed little or no 1 alpha-hydroxylase and substantial 24R-hydroxylase activity. Thyroparathyroidectomy of these rts markedly increased the 24R-hydroxylase activity.
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- Botham K. M., Ghazarian J. G., Kream B. E., DeLuca H. F. Isolation of an inhibitor of 25-hydroxyvitamin D3-1-hydroxylase from rat serum. Biochemistry. 1976 May 18;15(10):2130–2135. doi: 10.1021/bi00655a016. [DOI] [PubMed] [Google Scholar]
- Botham K. M., Tanaka Y., DeLuca H. F. 25-Hydroxyvitamin D3-1-hydroxylase. Inhibition in vitro by rat and pig tissues. Biochemistry. 1974 Nov 19;13(24):4961–4966. doi: 10.1021/bi00721a014. [DOI] [PubMed] [Google Scholar]
- Fraser D. R., Kodicek E. Unique biosynthesis by kidney of a biological active vitamin D metabolite. Nature. 1970 Nov 21;228(5273):764–766. doi: 10.1038/228764a0. [DOI] [PubMed] [Google Scholar]
- Garabedian M., Holick M. F., Deluca H. F., Boyle I. T. Control of 25-hydroxycholecalciferol metabolism by parathyroid glands. Proc Natl Acad Sci U S A. 1972 Jul;69(7):1673–1676. doi: 10.1073/pnas.69.7.1673. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gray R. W., Omdahl J. L., Ghazarian J. G., DeLuca H. F. 25-Hydroxycholecalciferol-1-hydroxylase. Subcellular location and properties. J Biol Chem. 1972 Dec 10;247(23):7528–7532. [PubMed] [Google Scholar]
- Henry H., Norman A. W. Presence of renal 25-hydroxyvitamin-D-1-hydroxylase in species of all vertebrate classes. Comp Biochem Physiol B. 1975 Mar 15;50(3):431–434. doi: 10.1016/0305-0491(75)90254-0. [DOI] [PubMed] [Google Scholar]
- Holick M. F., DeLuca H. F. A new chromatographic system for vitamin D3 and its metabolites: resoluation of a new vitamin D3 metabolite. J Lipid Res. 1971 Jul;12(4):460–465. [PubMed] [Google Scholar]
- Kream B. E., Reynolds R. D., Knutson J. C., Eisman J. A., DeLuca H. F. Intestinal cytosol binders of 1,25-dihydroxyvitamin D and 25-hydroxyvitamin D. Arch Biochem Biophys. 1976 Oct;176(2):779–787. doi: 10.1016/0003-9861(76)90222-8. [DOI] [PubMed] [Google Scholar]
- Lund J., DeLuca H. F. Biologically active metabolite of vitamin D3 from bone, liver, and blood serum. J Lipid Res. 1966 Nov;7(6):739–744. [PubMed] [Google Scholar]
- Midgett R. J., Spielvogel A. M., Coburn J. W., Norman A. W. Studies on calciferol metabolism. VII. The renal production of the biologically active form of vitamin D, 1,25-dihydroxycholecalciferol; species, tissue and subcellular distribution. J Clin Endocrinol Metab. 1973 Jun;36(6):1153–1161. doi: 10.1210/jcem-36-6-1153. [DOI] [PubMed] [Google Scholar]
- Napoli J. L., Fivizzani M. A., Hamstra A. J., Schnoes H. K., DeLuca H. F. Synthesis of 25-hydroxy[26,27-3h]vitamin D3 with high specific activity. Anal Biochem. 1979 Jul 15;96(2):481–488. doi: 10.1016/0003-2697(79)90610-9. [DOI] [PubMed] [Google Scholar]
- Neville P. F., DeLuca H. F. The synthesis of [1,2-3H]vitamin D3 and the tissue localization of a 0.25-mu-g (10 IU) dose per rat. Biochemistry. 1966 Jul;5(7):2201–2207. doi: 10.1021/bi00871a007. [DOI] [PubMed] [Google Scholar]
- Saarem K., Pedersen J. I., Tollersrud S. Soluble 25-hydroxyvitamin D3-1 alpha-hydroxylase from kidney mitochondria of rachitic pigs. Comp Biochem Physiol B. 1978;61(4):485–490. doi: 10.1016/0305-0491(78)90039-1. [DOI] [PubMed] [Google Scholar]
- Suda T., DeLuca H. F., Tanaka Y. Biological activity of 25-hydroxyergocalciferol in rats. J Nutr. 1970 Sep;100(9):1049–1052. doi: 10.1093/jn/100.9.1049. [DOI] [PubMed] [Google Scholar]
- Sunaga S., Horiuchi N., Takahashi N., Okuyama K., Suda T. The site of 1 alpha,25-dihydroxyvitamin D3 production in pregnancy. Biochem Biophys Res Commun. 1979 Oct 12;90(3):948–955. doi: 10.1016/0006-291x(79)91919-3. [DOI] [PubMed] [Google Scholar]
- Tahaka Y., Lorenc R. S., DeLuca H. F. The role of 1,25-dihydroxyvitamin D3 and parathyroid hormone in the regulation of chick renal 25-hydroxyvitamin D3-24-hydroxylase. Arch Biochem Biophys. 1975 Dec;171(2):521–526. doi: 10.1016/0003-9861(75)90061-2. [DOI] [PubMed] [Google Scholar]
- Tahaka Y., Lorenc R. S., DeLuca H. F. The role of 1,25-dihydroxyvitamin D3 and parathyroid hormone in the regulation of chick renal 25-hydroxyvitamin D3-24-hydroxylase. Arch Biochem Biophys. 1975 Dec;171(2):521–526. doi: 10.1016/0003-9861(75)90061-2. [DOI] [PubMed] [Google Scholar]
- Vieth R., Fraser D. Kinetic behavior of 25-hydroxyvitamin D-1-hydroxylase and -24-hydroxylase in rat kidney mitochondria. J Biol Chem. 1979 Dec 25;254(24):12455–12460. [PubMed] [Google Scholar]
- Yamada S., Schnoes H. K., DeLuca H. F. Synthesis of 25-hydroxy[23,24-3H]vitamin D3. Anal Biochem. 1978 Mar;85(1):34–41. doi: 10.1016/0003-2697(78)90270-1. [DOI] [PubMed] [Google Scholar]