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Study of steroid-protein binding by means of competitive adsorption: Application to cortisol binding in plasma

1967; Elsevier BV; Volume: 18; Issue: 3 Linguagem: Inglês

10.1016/0009-8981(67)90032-0

1873-3492

Walter Heyns, Hugo Van Baelen, Pieter De Moor,

Hormonal Regulation and Hypertension

The distribution of a steroid between a solution of steroid-binding proteins and a steroid-adsorbing solid added to this solution, depends not only on the properties of the adsorbent but also on the properties of the binding proteins and thus may be used for the study of steroid-protein interactions. Different types of distribution can be distinguished and were applied to the study of cortisol binding in plasma. (1) Endogenous steroids were removed from plasma by incubation with a rather large amount of adsorbent. (2) The cortisol-binding capacity of plasma transcortin was measured after incubation with a balanced amount of adsorbent and cortisol. (3) A relative index of cortisol-protein binding proportional to the ratio of bound to unbound cortisol, was determined by incubation of charcoal-treated plasma with a trace of [1,2-3H]cortisol and appropriate amounts of adsorbent. (4) From this relative index of cortisol—protein binding in plasma an estimate of the cortisol-binding affinity of plasma transcortin was derived.