SIMULTANEOUS ESTIMATION OF PLASMA CORTISOL AND TRANSCORTIN BINDING CHARACTERISTICS BY A COMPETITIVE PROTEIN BINDING TECHNIQUE

A slight modification of the competitive protein binding assay of Murphy (13) allows the simultaneous determination of plasma cortisol, transcortin binding capacity (Pt) and apparent transcortin-cortisol association constant (Kt). Pt and Kt may he derived from the standard curve data, usino the plasma under investiqation as the binding agent. The method is simple, reproducible and relatively rapid. The values obtained for Pt and Kt agree well with those found using other techniques. Many of the difficulties inherent in other methods used to study transcortin hindino characteristics are obviated. The authors stress the critical temperature dependence of values derived for Kt. © 1969.