1α,25-Dihydroxyvitamin D3-3β-bromoacetate, an Affinity-Labeling Analog of 1α,25-Dihydroxyvitamin D3 Receptor

In this communication we describe the synthesis of 1α,25-dihydroxyvitamin D3-3β-bromoacetate [1,25(OH)2-BE], an analog of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], as a part of our ongoing interest in characterizing the hormone-binding domain of the 1α,25-dihydroxyvitamin D3 receptor (VDR). We carried out several binding studies of 1,25(OH)2-BE with chick intestinal VDR preparations to demonstrate that 1,25(OH)2-BE is capable of blocking the entry of 1,25(OH)2D3 into its binding pocket and possibly covalently linking to the VDR molcule.