Synthesis of 1,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol by calvarial cells. Characterization of the enzyme systems.

J. E. Puzas, R. T. Turner, G. A. Howard, J. S. Brand, D. J. Baylink

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Abstract

The synthesis of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25(OH)2D3] from 25-hydroxycholecalciferol [25(OH)D3] has previously been shown to occur in cells isolated from bone. The main findings of the present study are that the enzyme systems which catalyse these syntheses are: (1) active at 'in vitro' substrate concentrations over the range of 2-50 nM; (2) regulatable in a complex way by 1,25(OH)2D3, 24,25(OH)2D3, 25,26-dihydroxycholecalciferol and 25(OH)D3, but not by cholecalciferol ('vitamin D3'); and (3) have relatively short half-lives (approx. 5 h).

Original languageEnglish (US)
Pages (from-to)333-338
Number of pages6
JournalThe Biochemical journal
Volume245
Issue number2
DOIs
StatePublished - Jul 15 1987

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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