Immunochemical Studies with Ovine Prolactin

Summary Quantitative measurements of antibody-prolactin precipitins formed in the test tube have demonstrated 3 zones of precipitation, decreasing in intensity with dilution of the antigen. The inhomogeneity of 3 preparations of purified prolactin has been demonstrated immunochemically by the formation of multiple precipitin bands in agar gel. Prolactin fractions were prepared by countercurrent distribution, by chromatography on DEAE-C column and by filtration through Sephadex G-100. These fractions differed in biological activity. The fractions obtained in countercurrent distribution and DEAE-C fractions were found to be unstable, losing 90 to 95% of their activity, while the unfractionated prolactin remained stable. Precipitation by antibody occurred whether prolactin fractions were fully potent or had lost activity. Fractionation by countercurrent distribution and by chromatography on DEAE-C column separated components which diffused at different rates and precipitated with antibody to form 2 distinct bands in agar gel. The continuity of these bands with those of the original material identified them with the original source material.