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Steroid–protein interactions Kinetics of binding of cortisol and progesterone to human corticosteroid‐binding globulin
Author(s) -
Stroupe S.D.,
Gray R.D.,
Westphal U.
Publication year - 1978
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(78)80099-4
Subject(s) - transcortin , steroid , kinetics , receptor–ligand kinetics , chemistry , globulin , endocrinology , medicine , corticosteroid , plasma protein binding , biochemistry , biology , hormone , receptor , physics , quantum mechanics
Human corticosteroid-binding globulin is the first high-affinity steroid binding protein that has been studied in detail [l--S J . Although its general physicochemical parameters (molecular weight, absorptivity, carbohydrate and amino acid content) have been defined, further information related to steroid binding of CBG” is needed. It is noteworthy that the rather unusual progesterone binding globulin (PGB), obtained from pregnant guinea pig serum, has been more thoroughly characterized with respect to specificity [6-81 and with respect to mechanism of binding [9111 than has human CBG . The sensitive method of stopped-flow fluorescence has been applied to explore the mechanism of binding of steroids to human CBG. The binding of steroids to various proteins results in quenching of the intrinsic fluorescence of the protein [9] . The large decrease in fluorescence which occurs upon the binding of 3-oxopene steroids to PBG has been used to measure the rates of complex formation and dissociation [ 1 I] . We have recently demonstrated the generality of the fluorescence quenching method in determinations of the dissociation rate constants of human CBGsteroid com-