Question of Purity of Erythropoietic Factor Concentrates.

Abstract
The bulk of erythropoietic activity of anemic rabbit plasma can be concentrated in a mucoprotein fraction which represents less than 0.5% of plasma proteins. Yet from the similarity in yield and electrophoretic behavior of the corresponding inactive fraction from normal plasma, it appears likely that the erythropoietic factor constitutes only a small portion of the present concentrates.
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