Interaction of steroid-binding serum proteins with concanavalin A-Sepharose 4B

The interaction between steroid-finding serum proteins and concanavalin A was studied using affinity chromatography on concanavalin A-Sepharose 4B. The sex hormone-binding globulins of man and rabbit together with the corticosteroid-binding globulins of man, rabbit and guinea pig were all bound quantitatively by the affinity medium. Only two thirds of rat corticosteriod-binding globulin showed an affinity for concanavalin A indicating this protein to be heterogeneous with respect to terminal mannose or glucose residues. The progesterone-binding globulin in pregnant guinea pig serum, possessing the highest carbohydrate content of the proteins investigated, did not bind to concanavalin A-Sepharose 4B. Affinity chromatography on concanavalin A-Sepharose 4B is documented to be a valuable supplement to existing methods for analysing steroid-protein interactions.