Steroid-protein interactions—XXXVIII. Influence of steroid structure on affinity to the progesterone-binding globulin

Steroid-protein interactions. Human corticosteroid binding globulin: some physicochemical properties and binding specificity

“…Similar results have also been observed in the case of guinea pig CBG . Guinea pig PBG, however, binds the 5adihydro derivative much better (6-fold) than the 5/3-dihydro derivative (Blanford et al, 1978).…”

“…The steroid binding site of guinea pig PBG is predominantly hydrophobic in nature (Blanford et al, 1978) while the binding site in guinea pig CBG contains several hydrophilic residues capable of interacting with the hydroxy and oxo groups of cortisol . Since human CBG binds cortisol and progesterone with essentially the same affinity, hydrophilic groups capable of forming hydrogen bonds with the three hydroxy groups of cortisol may be missing in human CBG.…”

Steroid-protein interactions. 43. Influence of steroid structure and temperature on the binding of steroids to guinea pig corticosteroid-binding globulin

“…CBG was purified by affinity chromatography, hydroxylapatite, and gel filtration as previously described (Mickelson & Westphal, 1979a). The steroids used were from our collection obtained over the years from commercial sources or research laboratories as previously acknowledged (Blanford et al, 1978). Steroid solutions were prepared and concentrations were verified by using the molar absorptivities as previously published (Blanford et al, 1978).…”

“…The steroid binding site of guinea pig CBG appears to be best adapted to bind cortisol, the predominant corticosteroid in the guinea pig; alteration of this structure invariably decreases the affinity. In contrast to the steroid-binding site of the guinea pig PBG, which is predominantly hydrophobic in nature (Blanford et al, 1978), the binding site of CBG apparently has more hydrophilic groups capable of interacting with the hydroxy and oxo groups of cortisol. Based on studies of steroid binding to human CBG (Murphy, 1969; unpublished results from this laboratory) and on the present results, it is concluded that the steroid-binding site of guinea pig CBG is more specific in comparison with human CBG which binds cortisol, progesterone, and certain other steroids with a similar affinity.…”

2D and 3D QSAR studies of the receptor binding affinity of progestins

“…In the past, a number of papers were published on the observed receptor binding affinities of progestins to human cytosol receptor proteins. [5][6][7][8][9][10][11] Because of the wide applicability of progestins for human health problems, it is desirable to investigate their receptor binding affinity. Saha et al 12 performed a quantitative structure activity relationship (QSAR) analysis of the receptor binding affinity of twenty four progestins (P1-P24) with the electrotopological state atom index (ETSA), 13 in an attempt to locate the pharmacophore fragment of the molecule.…”