Steroid-protein interactions. XV. Isolation and characterization of corticosteroid-binding globulin from human plasma.

摘要: Abstract Corticosteroid-binding globulin was isolated from normal human plasma by successive anion exchange chromatography and gel filtration. Ammonium sulfate fractionation employed as a preliminary step when large volumes were processed. The purification about 4000-fold. Homogeneity shown free boundary, agar paper electrophoresis, sedimentation velocity, diffusion. Immunoelectrophoretic behavior against antisera to serum fractions indicated purity. Other immunoelectrophoretic analyses showed lack of reaction with produced sera several species other than human. molecular weight the protein calculated 51,700 diffusion data. Chemical composition ascertained amino acid carbohydrate analyses, nitrogen determination, biuret. physicochemical properties described include coefficient (s020,w = 3.79 S), (D20,w 6.15 x 10-7 cm2 sec-1), electrophoretic mobility (u 4.9 10-5 volt-1 extinction (E1%1 cm 6.45), partial specific volume (V 0.708 ml g-1), frictional ratio (f/f0 1.42). One binding site for cortisol found equilibrium dialysis at 4° 37°; association constants these temperatures 5.2 108 m-1 2.4 107 m-1, respectively. Complete removal sialic did not significantly affect cortisol-binding affinity. Pure corticosteroid-binding inactivated filtration 45° or glass-redistilled water.