title: The rate of triiodothyronine dissociation from binding sites in human plasma.
abstract: A method is described for estimating the rate of triiodothyronine (T3) dissociation from binding sites in human plasma. At trace concentration about 25% of the hormone dissociates rapidly, the reaction being more than half complete within 1 second. The remaining 75% dissociates exponentially with a t1/2 of 4.2 seconds at 37-38 degrees C. When the plasma is loaded with thyroxine to displace the T3 from thyroxine-binding globulin, the slow exponential reaction is lost and all of the hormone dissociates rapidly. These results indicate that the free and bound T3 in plasma are in a state of rapid exchange.
mesh_terms: D001665:Binding Sites; D006801:Humans; D008722:Methods; D013975:Thyroxine-Binding Proteins / Q000378:metabolism; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine