Effect of 1,10-phenanthroline on DNA binding by 1,25-(OH)2 vitamin D receptor.

The effect of the chelator 1,10-phenanthroline on the DNA-binding of 1,25-dihydroxyvitamin D receptor was demonstrated. Increasing concentrations of the chelator, up to 3 mM, decreased receptor binding to DNA-cellulose. This effect was specific for the chelating function because the nonchelating analog, 1,7-phenanthroline, did not inhibit DNA-cellulose binding of the receptor. The cations Cd2+ and Zn2+ were able to block chelator-mediated inhibition. These cations were unable to reverse the inhibition unless 1,10-phenanthroline was removed by dialysis.