ISOMERIZATION OF RADIOACTIVE ALDOSTERONE AT C-17: ENZYMIC PURIFICATION OF THE 17α- AND β-ISOMERS

Abstract
Commercial supplies of [16-3H]aldosterone and [1,2-3H]aldosterone (18-formyl-11β,21-dihydroxy-4-pregnene-3,20-dione) received in this laboratory have been found to be considerably contaminated with 17α-isomer, 'iso-aldosterone' (A. Cameron, E. Allsop & J. D. H. Slater, unpublished results). It is essential to use the pure tracer only, when carrying out metabolic experiments, e.g. determinations of the aldosterone secretion rate based on the specific activity of an exclusive urinary metabolite. The isomers can be partly separated by chromatography in the Bush B5 system (Bush, 1961), but only occasionally can an aldosterone spot, completely free of iso-aldosterone, be obtained by this method. However, the diacetates of the isomers can be easily and fully separated by chromatography in the cyclohexane (C):benzene (B):methanol (M):water (W) (100:50:100:25) system of Kliman & Peterson (1960). Cortisone acetate (17α-hydroxy-4-pregnene-3,11,20-trione, 21-monoacetate) has been hydrolysed to free cortisone by means of pseudocholinesterase (Hobbiger, Simpson & Tait (1954) and this enzymic

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