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Ortiz-Boyer F, Fernández-Romero JM, Castro MDLD, Quesada JM. Improved Procedure for the Dual Cartridge Cleanup of Hydroxyvitamin D3Metabolites in Plasma. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826079808001236] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- F. Ortiz-Boyer
- a Department of Analytical Chemistry Faculty of Sciences , University of Córdoba , E-14004, Córdoba, Spain
| | - J. M. Fernández-Romero
- a Department of Analytical Chemistry Faculty of Sciences , University of Córdoba , E-14004, Córdoba, Spain
| | - M. D. Luque de Castro
- a Department of Analytical Chemistry Faculty of Sciences , University of Córdoba , E-14004, Córdoba, Spain
| | - J. M. Quesada
- b Mineral Metabolism Unit , Hospital Reina Sofía University of Córdoba , E-14004, Córdoba, Spain
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Eto TA, Nakamura Y, Taniguchi T, Miyamoto K, Nagatomo J, Maeda Y, Higashi S, Okuda K, Setoguchi T. Assay of 25-hydroxyvitamin D3 1 alpha-hydroxylase in rat kidney mitochondria. Anal Biochem 1998; 258:53-8. [PMID: 9527847 DOI: 10.1006/abio.1998.2567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An assay method for 25-hydroxyvitamin D3 1alpha-hydroxylase [calcidiol, NADPH: oxygen oxidoreductase (1-hydroxylating), EC 1.14. 13.13] in rat kidney is described. The mitochondrial and nuclear fraction was solubilized effectively with 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate(Chaps). By subsequent ultracentrifugation of the solubilized suspension the effect of inhibitory factor(s) in mammals was removed. The enzyme was then assayed by the reconstitution method using saturated amounts of adrenodoxin and NADPH-adrenodoxin reductase. Products were analyzed by HPLC, monitoring absorbance at 265 nm. The enzyme activity depended on not only pH of the medium but also the kind of buffers. N,N-Bis(2-hydroxyethyl)glycine was the best buffer. At 30 degrees C, the reaction velocity was linear at least up to 10 min, by which time enough amounts of the product needed for analysis were formed. The enzyme activity was linear to a protein concentration up to 0.8 mg of protein/ml. Under the best assay conditions established, the maximal velocity of enzyme in the rachitic rat was 12.9 pmol of product/min/mg of protein, which was 30- to 1000-fold higher than those reported by other authors with the enzyme of rachitic rat. Michaelis constant was 1.8 microM. Specific activity with the enzyme of normal rat was 0.25 pmol of product/min/mg.
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Affiliation(s)
- T A Eto
- Department of Surgery I, Miyazaki Medical College, Kiyotake, 889-16, Japan
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Boyer FO, Fernández Romero JM, Luque de Castro MD, Quesada JM. Aminopropyl-silica as an advantageous alternative to nonpolar sorbents for continuous cleanup/preconcentration of vitamin D3 metabolites. Chromatographia 1998. [DOI: 10.1007/bf02466466] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Ballesteros E, Gallego M, Valcárcel M. A gas chromatographic flow method for preconcentration and determination of vitamins D2 and D3 in pharmaceutical preparations. Chromatographia 1995. [DOI: 10.1007/bf02269907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Hagenfeldt Y, Berlin T. The human renal 25-hydroxyvitamin D3-1 alpha-hydroxylase: properties studied by isotope-dilution mass spectrometry. Eur J Clin Invest 1992; 22:223-8. [PMID: 1499638 DOI: 10.1111/j.1365-2362.1992.tb01455.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The renal 25-hydroxyvitamin D3-1 alpha-hydroxylase activity has been measured in normal human kidney cortex, using a highly specific assay based on isotope-dilution mass spectrometry. The cortex was obtained from kidneys removed due to renal tumours. The subcellular distribution of 25-hydroxyvitamin D3-1 alpha-hydroxylase activity was studied. Enzyme activity was only observed in the mitochondrial fraction. Mitochondria from non-tumourous kidney cortex had a Vmax of 0.17 +/- 0.02 pmol min-1 mg-1 protein and the apparent Km was in the range of 14 mumol l-1. There was a tendency to a higher 25-hydroxyvitamin D3-1 alpha-hydroxylase activity in preparations from male kidney (0.21 +/- 0.03 pmol min-1 mg-1 protein) than female (0.12 +/- 0.02, P less than 0.05). A significant inverse correlation between serum phosphate and 25-hydroxyvitamin D3-1 alpha-hydroxylase activity was found. No correlation was observed between enzyme activity and serum levels of 1,25-dihydroxyvitamin D (total and free index), PTH, total calcium or ionized calcium. The results indicate that there is a sex difference in human 25-hydroxyvitamin D3-1 alpha-hydroxylase activity similar to the one observed in laboratory animals. Furthermore, the data support the hypothesis that serum phosphate is a major regulator of 1,25-dihydroxyvitamin D3 production in man.
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Affiliation(s)
- Y Hagenfeldt
- Department of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden
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6
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Watson D, Setchell KD, Ross R. Analysis of vitamin D and its metabolites using thermospray liquid chromatography/mass spectrometry. Biomed Chromatogr 1991; 5:153-60. [PMID: 1655127 DOI: 10.1002/bmc.1130050404] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A new method is described for the analysis of vitamin D and its metabolites utilizing thermospray (TSP) mass spectrometry as an on-line detector for high performance liquid chromatography. Ionization conditions were optimized for use with isocratic reversed phase chromatography. TSP mass spectrometry was employed in series with a UV absorbance detector to facilitate comparisons between the two methods of detection. Positive ion TSP mass spectra were recorded for vitamin D2, vitamin D3, 25-hydroxyvitamin D3 (25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3). The spectra contained protonated molecular ions, ammonium adduct ions and fragment ions due to the loss of one or more molecules of water. A comparison of quantitative precision was made by determining UV absorbance and TSP standard curves for vitamin D3 using two different methods: (1) External standard method with post-column (post UV detector) addition of ammonium acetate. (2) As (1) but using the method of internal standards with a closely eluting internal standard (vitamin D2). In each case the quantitative precision (correlation coefficient) for UV absorbance detection was superior owing to intrinsic instability of the TSP ion beam. A stable isotopically labelled internal standard was employed in the development of an assay for 1,25(OH)2D3. The assay was used to quantify in vitro enzymic conversion of 25(OH)D3 to 1,25(OH)2D3 in guinea pig and sheep renal mitochondrial incubations. TSP LC/MS was also applied to analysis of an extract of human blood plasma in which D3 and each of its principal metabolites were identified in a single analysis.
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Affiliation(s)
- D Watson
- Mass Spectrometry Laboratory, Children's Hospital Medical Center, Cincinnati, Ohio 45229
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7
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Postlind H. Separation of the cytochromes P-450 in pig kidney mitochondria catalyzing 1 alpha-, 24- and 26-hydroxylations of 25-hydroxyvitamin D3. Biochem Biophys Res Commun 1990; 168:261-6. [PMID: 2328005 DOI: 10.1016/0006-291x(90)91702-t] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cytochromes P-450 in pig kidney mitochondria catalyzing 1 alpha-, 24- and 26-hydroxylations of 25-hydroxyvitamin D3 have been separated. The cytochrome P-450 fractions required NADPH, mitochondrial ferredoxin and ferredoxin reductase for catalytic activity. The present report demonstrates that different forms of cytochrome P-450 are involved in 1 alpha-, 24- and 26-hydroxylations of 25-hydroxyvitamin D3 and provides a basis for further purification and characterization of these enzymes.
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Affiliation(s)
- H Postlind
- Department of Pharmaceutical Biochemistry, University of Uppsala, Sweden
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Postlind H, Wikvall K. Evidence for the formation of 26-hydroxycholesterol by cytochrome P-450 in pig kidney mitochondria. Biochem Biophys Res Commun 1989; 159:1135-40. [PMID: 2930554 DOI: 10.1016/0006-291x(89)92227-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pig kidney mitochondria were found to catalyze the formation of 26-hydroxycholesterol, an inhibitor of cholesterol biosynthesis. The cholesterol 26-hydroxylase was purified 600-fold. It was present in a mitochondrial enzyme fraction enriched in cytochrome P-450. The cytochrome P-450 fraction required NADPH, mitochondrial ferredoxin and ferredoxin reductase for 26-hydroxylase activity. The mitochondria and the purified 26-hydroxylase preparation also catalyzed 26-hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol, and intermediate in cholic acid biosynthesis, and of 25-hydroxyvitamin D3. The role of extra-hepatic formation of 26-hydroxycholesterol is discussed.
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Affiliation(s)
- H Postlind
- Department of Pharmaceutical Biochemistry, University of Uppsala, Sweden
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9
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Hagenfeldt Y, Eriksson H, Björkhem I. Stimulatory effect of testosterone on renal 25-hydroxyvitamin D-3 1 alpha-hydroxylase in guinea pig. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1002:84-8. [PMID: 2923868 DOI: 10.1016/0005-2760(89)90068-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Castration of male guinea pigs reduced the activity of the renal mitochondrial 25-hydroxyvitamin D-3 1 alpha-hydroxylase by about 50% without affecting the apparent Km for the reaction. Testosterone substitution for 10 days after castration increased the activity to about the same level as that of sham-operated animals. Ovariectomy of female guinea pigs had no effect on the 1 alpha-hydroxylase activity. Administration of testosterone to ovariectomized female guinea pigs increased the activity by about 50%, again without affecting the apparent Km. The different manipulations had no significant effect on circulating levels of 1,25-dihydroxyvitamin D or vitamin D-binding protein (DBP). It is concluded that testosterone may be a regulator of the 25-hydroxyvitamin D-3 1 alpha-hydroxylase in guinea pigs.
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Affiliation(s)
- Y Hagenfeldt
- Department of Clinical Chemistry, Huddinge Hospital, Sweden
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10
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Dusso A, Lopez-Hilker S, Rapp N, Slatopolsky E. Extra-renal production of calcitriol in chronic renal failure. Kidney Int 1988; 34:368-75. [PMID: 3172645 DOI: 10.1038/ki.1988.190] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Renal 1-alpha-hydroxylase activity is tightly regulated in normal humans and intact animals. No significant changes in serum 1,25(OH)2D levels occur in response to vitamin D challenge. However, conflicting reports have appeared in the literature with regard to stimulation of 1,25(OH)2D production after 25(OH)D administration in uremia. To provide further insight into this issue, 25(OH)D at a dose of 100 micrograms every other day for two weeks followed by 50 micrograms every other day for the next two weeks was given orally to seven uremic mongrel dogs. After two weeks of 25(OH)D therapy, 1,25(OH)2D levels increased from 16.4 +/- 0.9 to 28.0 +/- 1.9 pg/ml (P less than 0.001) in parallel with a fourfold increase in 25(OH)D concentrations from a basal of 50.1 +/- 6.5 to 203.2 +/- 18.1 ng/ml. No significant changes in serum i-PTH, ICa or P were observed. Linear regression analysis of the relationship between serum concentrations of 1,25(OH)2D versus 25(OH)D, for each dog during this period, showed highly significant correlation coefficients. To evaluate the possibility that extra-renal sites contribute to the described enhanced 1,25(OH)2D net synthesis after 25(OH)D treatment, similar studies were performed in four anephric patients undergoing hemodialysis. Basal serum 1,25(OH)2D levels were 5.5 +/- 2.4 pg/ml and increased to 19.6 +/- 5.0 pg/ml after 25(OH)D administration. A significant correlation was also found for the relationship between serum levels of 1,25(OH)2D and 25(OH)D in anephrics (r = 0.72, P less than 0.001). The same therapy in four normal volunteers showed no significant changes in serum 1,25(OH)2D concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Dusso
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
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11
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Oftebro H, Falch JA, Holmberg I, Haug E. Validation of a radioreceptor assay for 1,25-dihydroxyvitamin D using selected ion monitoring GC-MS. Clin Chim Acta 1988; 176:157-68. [PMID: 3180464 DOI: 10.1016/0009-8981(88)90203-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This report describes two methods for the measurement of 1,25-dihydroxyvitamin D [1,25(OH)2D] in serum: A modified radio receptor assay (RRA), employing a 1,25(OH)2D receptor from calf thymus, and selected ion monitoring (SIM) with combined capillary gas chromatography (GC)-mass spectrometry (MS). The intra-assay coefficient of variation was close to 13% for both methods, and the inter-assay coefficients of variation were 14.0 and 6.5% for RRA and SIM (GC-MS), respectively. Aliquots of 2 ml (RRA) and 20 ml (SIM) serum were used, and the limits of detection were 10 and 6 pmol/l, respectively. The analytical recovery of each method was assessed, and a maximum deviation from the expected value of 10 and 2% was found for RRA and SIM, respectively. A correlation coefficient of 0.93 (slope 0.97) was obtained when 27 different serum samples were analyzed by both methods. Included in this study were serum samples from healthy subjects and patients with subnormal as well as supranormal 1,25(OH)2D levels. This result showed that the RRA accurately measured the serum levels of 1,25(OH)2D and therefore should be useful in the diagnosis and control of vitamin D dependent diseases.
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Affiliation(s)
- H Oftebro
- Hormone Laboratory, Aker Hospital, Oslo, Norway
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12
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De Leenheer AP, Nelis HJ, Lambert WE, Bauwens RM. Chromatography of fat-soluble vitamins in clinical chemistry. JOURNAL OF CHROMATOGRAPHY 1988; 429:3-58. [PMID: 3062023 DOI: 10.1016/s0378-4347(00)83866-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A review is presented of current gas and liquid chromatographic methods for the determination of the fat-soluble vitamins A, D, E and K and the provitamin A beta-carotene in biological samples of human origin. For each vitamin, the discussion successively focuses on procedures for sample preparation, gas and liquid chromatographic systems and principles of detection. The emphasis is on liquid chromatography, which is gradually becoming a standard technique in fat-soluble vitamin assays. New trends in the liquid chromatography of these compounds include the use of smaller particles and shorter columns, to improve speed, and the advance of electrochemical detection as an alternative to absorbance and fluorescence detection. Bonded phases, both normal and reversed phase, tend to be preferred over underivatized silica as column supports. Gas chromatography remains of particular value in combination with mass spectrometry, a technique which may form the basis of reference methods. In general, despite the availability of well established analytical methods for fat-soluble vitamins, the wealth of recent literature in this area indicates that there continues to be a need for new assays with enhanced speed, specificity and sensitivity.
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Affiliation(s)
- A P De Leenheer
- Laboratoria voor Medische Biochemie, Klinische Analyse, Ghent, Belgium
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13
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Pedersen JI, Hagenfeldt Y, Björkhem I. Assay and properties of 25-hydroxyvitamin D3 23-hydroxylase. Evidence that 23,25-dihydroxyvitamin D3 is a major metabolite in 1,25-dihydroxyvitamin D3-treated or fasted guinea pigs. Biochem J 1988; 250:527-32. [PMID: 3355535 PMCID: PMC1148887 DOI: 10.1042/bj2500527] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Incubation of 25-hydroxyvitamin D3 with kidney cortex mitochondria from 1,25-dihydroxyvitamin D3-treated guinea pigs resulted in the formation of 23,25-dihydroxyvitamin D3 as the major product. The identity of the product was verified by g.c.-m.s. and quantification was performed by h.p.l.c. The rates of the reaction were in the range 1.0-1.8 pmol/min per mg of mitochondrial protein (at 37 degrees C), which were 5-10 times the rates of formation of 24,25-dihydroxyvitamin D3. In mitochondrial preparations from untreated guinea pigs, the rate of 23-hydroxylation was below detection limit (0.02 pmol/min per mg of mitochondrial protein). Fasting the animals for 24 h induced the 23-hydroxylase almost as efficiently as treatment with 1,25-dihydroxyvitamin D3, with a concomitant depression of the 1 alpha-hydroxylase. The 23-hydroxylase reaction required oxidizable substrate, was decreased by low O2 partial pressures and inhibited by CO or the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone. It was stimulated by the respiratory-chain inhibitors rotenone, antimycin A and KCN. These results indicate that the guinea-pig renal mitochondrial 23-hydroxylase is a cytochrome P-450 and that the reducing equivalents are primarily supplied by NADPH via the energy-dependent transhydrogenase.
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Affiliation(s)
- J I Pedersen
- Institute for Nutrition Research, School of Medicine, University of Oslo, Norway
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Hagenfeldt Y, Pedersen JI, Björkhem I. Properties of guinea-pig kidney 25-hydroxyvitamin D3 1 alpha-hydroxylase assayed by isotope dilution-mass spectrometry. Biochem J 1988; 250:521-6. [PMID: 3281665 PMCID: PMC1148886 DOI: 10.1042/bj2500521] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
1. A highly specific and accurate method based on isotope dilution-mass spectrometry was used for characterization of the renal 25-hydroxyvitamin D3 1 alpha-hydroxylase in untreated guinea pigs with a normal vitamin D status. In previous work, the properties of the enzyme had been determined in rachitic animals only. 2. With intact mitochondria, the reaction required the presence of citric acid-cycle intermediates. The uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone had an inhibitory effect on the isocitrate-supported reaction, indicating that energy-dependent transhydrogenation is of importance. Mitochondrial respiratory-chain inhibitors (cyanide, rotenone, antimycin A) had no effect on the hydroxylation. CO had an inhibitory effect, suggesting participation of a species of cytochrome P-450 in the reaction. A fraction solubilized from mitochondria by cholate became catalytically active in 1 alpha-hydroxylation of 25-hydroxyvitamin D3 after addition of ferredoxin and ferredoxin reductase. The isocitrate-supported reaction catalysed by crude mitochondria had an apparent Km of about 1 microM. 3. An atmosphere containing 50% O2 was found to be necessary for optimal activity. It is thus possible that O2 may be a limiting factor under normal conditions in vivo. 4. The results demonstrate that the mammalian renal 25-hydroxyvitamin D3 1 alpha-hydroxylase is a cytochrome P-450-dependent mixed-function oxidase with properties similar to those previously reported for the same enzyme system in chicken. The present assay and animal system seem to be suitable for further studies on the mechanism of regulation of the mammalian renal 25-hydroxyvitamin D3 1 alpha-hydroxylase under conditions when the vitamin D status is normal.
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Affiliation(s)
- Y Hagenfeldt
- Department of Clinical Chemistry, Huddinge Hospital, Stockholm, Sweden
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