Human urinary erythropoietin: preparation with high potency.

Human urinary erythropoietin has been purified to homogeneity. The seven-step procedure yielded a preparation with a potency of 225,000 U/mg protein. SDS-polyacrylamide gel electrophoretic analysis of the purified hormone revealed a single protein band with a molecular weight of about 35,000 that migrated with the biological activity. As to its stability, the purified hormone retained its activity in the presence of 0.001%Tween 20.