Partial Purification of Urinary Erythropoietin. ∗

Summary

Urinary erythropoietic factor has been partially purified by adsorption on kaolin followed by serial elution with ammonium acetate buffers of increasing pH and then with 1 M NH₄OH. Using this procedure, a 39% yield with a 230 fold purification of the active factor has been obtained. The purified preparation of the active factor produces metachromasia with toluidine blue, has an absorption peak at 280 mμ, and migrates very slowly on paper strips in an electrophoretic apparatus. The similarity and differences between urinary and plasma erythropoietin are discussed.