Corticosteroid-Binding Globulin: Species Distribution and Small-Scale Purification

Abstract

The sera of 25 vertebrate species from the vertebrate classes Pisces, Amphibia, Reptilia, Aves and Mammalia, and including representatives of the orders Lagomorpha, Rodentia, Carnivora, Perissodactyla, Artiodactyla and Primates from the class Mammalia, have been examined for the presence of a specific corticosteroid-binding protein. Binding activity was assayed by means of gel nitration on Sephadex G-50. The amount of binding at 4 and 37 C was assayed and the sensitivity of binding to heating at 60 C was determined. The sera of all species examined exhibited binding activity which was temperature-dependent and sensitive to heating. A small-scale purification procedure for human corticosteroid-binding globulin on hydroxylapatite is described and its applicability to the cortisol-binding protein of 7 other species is demonstrated.