title: Purification and characterization of the corticosteroid-binding globulin of pregnant guinea pig serum.
abstract: The corticosteroid-binding globulin from guinea pig pregnancy serum was purified by the sequential use of affinity chromatography, hydroxylapatite chromatography, and gel filtration chromatography at a cumulative yield of 80%. The protein was found to be homogeneous by analytical gel electrophoresis, equilibrium sedimentation ultracentrifugation, immunoelectrophoresis, and stoichiometry (1:1) of steroid binding. Guinea pig corticosteroid-binding globulin has a molecular weight of 43 300 and contains 29% carbohydrate. The intrinsic fluorescence of the corticosteroid-binding globulin is quenched by about 73% when 1 mol of cortisol is bound. The association constants (pH 7.4) at 4 and 37 degrees C are 2.5 X 10(7) and 1.5 X 10(6) M-1 for cortisol and 1.4 X 10(6) and 0.2 X 10(6) M-1 for progesterone, respectively.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D005260:Female; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000378:metabolism; D007122:Immunoelectrophoresis; D007700:Kinetics; D008970:Molecular Weight; D011247:Pregnancy; D011270:Pregnancy, Animal; D011374:Progesterone / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014156:Transcortin / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D011374:Progesterone; D014156:Transcortin; D006854:Hydrocortisone