PARTIAL PURIFICATION AND PRELIMINARY CHARACTERIZATION OF ESTROGEN-BINDING GLOBULINS FROM HUMAN PLASMA

This report concerns the partial isolation and preliminary characterization of an estradiol-binding globulin from human plasma. Sequential fractionation with ammonium sulfate, DEAE-cellulose, and Sephadex G-200 yielded at least two proteins which bind estradiol, both of which have the mobility of β-globulins. The larger of the two globulins has a molecular weight of 420,000 andthe smaller a weight of 135,000 as determined by chromatography on a calibrated column of Sephadex.The larger protein has two association constants for estradiol at 4C: 1.7 × 109and 0.12 × 109 m-1. The smaller protein has three association constants for estradiol at 4C: 4.0 × 109, 0.69 × 109, and 0.11 × 109m-1. © 1969, American Chemical Society. All rights reserved.