Studies on the Purification of Rat Prolactin from Anterior Pituitary Organ Culture by Preparative Disc Electrophoresis

Abstract

Anterior pituitaries (AP) from female rats were cultured in medium 199 for 3 days and the prolactin released into the medium purified by preparative disc electrophoresis. Medium enriched with prolactin by increasing the AP tissue/medium ratio during culture was layered on top of a 2.5-percent spacer gel and separated in 7.5% gel using 40 mA throughout the experiment. A total of 3.4 mg of prolactin was obtained which was homogenous by both analytical disc electrophoresis and immunodiffusion. The specific prolactin activity was determined by preparing the sample using spectrophotometric and weight methods. In the former case the activity was 28.4 ± 1.6 IU/mg while in the latter case the activity was 24.9 ± 1.9; the difference was not statistically significant (p > 0.05). Preparative disc electrophoresis of 3-day culture medium resulted in a prolactin yield of 27 mg/g of wet weight AP. This yield is the highest reported to-date for purified rat prolactin.