Synthesis of biotin-labelled dexamethasone derivatives: novel hormone-affinity probes

A new, general methodology for ‘sandwich’ affinity chromatography of steroid hormone receptors is proposed, the part purification of the human spleen tumor glucocorticoid receptor is quoted as an illustration. 9-Fluoro-16α-methyl-11β,17-dihydroxy-1,4-androstadiene-3-one-17β-carboxylic acid was coupled to biotin using pentamethylenediamine (BioDex 1) as a spacer. The bifunctional derivative binds to glucocorticoid receptors and avidin-Sepharose and efficiently protects the glucocorticoid receptor against inactivation when previously added during homogenisation. We have standardized the capacity and optimum conditions for elution of receptor - BioDex-1 complexes which are bound to avidin-Sepharose. Receptor purification of several thousandfold can be obtained with good yield.