title: An 125I-labeled cortisol radioimmunoassay in which serum binding protein are enzymatically denatured.
abstract: We report an iodine-125 radioimmunoassay for cortisol in biological fluids, in which interfering binding proteins are enzymatically denatured. An antiserum to cortisol-3-carboxymethyloxime-bovine serum albumin, extremely low cross-reacting with other corticosteroids, was raised in rabbits. A cortisol-3-carboxymethyloxime tyrosine methyl ester derivative was synthesized and labeled with iodine-125 by standard radioiodination techniques. To eliminate the need for extraction and recovery procedures, we digested interfering binding witha proteolytic enzyme, which then was heat-inactivated before adding the labeled derivative and the premixed, preincubated antiserum complex. There was quantitative analytical recovery of esogenous cortisol added to sera from a normal man, a normal woman, and a pregnant woman. Values for the same samples agreed after extraction and chromatographic purification and agreed well with values obtained by other techniques by independent reference laboratories. The five-step assay can be done in 6 h or less.
mesh_terms: D001798:Blood Proteins; D003429:Cross Reactions; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007457:Iodine Radioisotopes; D008297:Male; D008832:Microchemistry; D011247:Pregnancy; D011489:Protein Denaturation; D011786:Quality Control; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D001798:Blood Proteins; D007457:Iodine Radioisotopes; D006854:Hydrocortisone