title: Studies on the mode of action of calciferol XXV. 1 alpha,25-dihydroxy-5,6-trans-vitamin D3, the 5E-isomer of 1 alpha,25-dihydroxyvitamin D3.
abstract: A structural analog of 1 alpha,25-dihydroxyvitamin D3 has been examined for biological activity and its ability to interact with the 1 alpha,25-dihydroxyvitamin D3 receptor system from chick intestine. This steroid, 1 alpha,25-dihydroxy-5,6-trans-vitamin D3, is the 5E-isomer of the parent molecule which differs from that molecule only in the position of the exocyclic C-19 methylene group. This new compound allows for the first direct assessment of the relative contribution of this A-ring substituent to ligand-receptor interaction and biological activity. This analog was found to be 6--12% as biologically active as the parent hormone and 13% as effective in binding to the intestinal receptor.
mesh_terms: D000818:Animals; D002117:Calcitriol; D002118:Calcium / Q000378:metabolism; D002645:Chickens; D004100:Dihydroxycholecalciferols / Q000378:metabolism* / Q000494:pharmacology; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism; D008297:Male; D011869:Radioligand Assay; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002117:Calcitriol; D002118:Calcium