Figure 3.

Hydrophobic-interaction chromatography (HIC) of FPE. Approximately 56 pituitaries were extracted twice with 0.5 ml 1.2 M (NH₄)₂SO₄ in 0.1 M sodium phosphate buffer (pH 6.8) and the extracts were combined, centrifugally filtered, and applied to a Phenyl-5-PW column via the 10-ml Superloop. The effluent was monitored for UV-absorbance (A) and a linear gradient of decreasing (NH₄)₂SO₄ concentration was started after the unadsorbed protein eluted from the column. Fractions of 1.0 ml were collected and tested for (B) maturational and (C) steroidogenic activity. Two peaks of E₂-generating activity are indicated (a, b). For this experiment only, positive controls (FPE added at a concentration of 0.5 pit. equiv./well) were 50% GVBD with DHP-, T-, and E₂-secretion of 1.3, 0.8, and 7.4 ng/well, respectively.