On the Chemical Nature of the Reticulocyte Ripening Principles in Liver

Abstract

Summary. The reticulocyte ripening principle in liver extracts consists of a thermolabile fraction which can be absorbed by floridin and a thermostable fraction which cannot be absorbed by floridin. The latter fraction has only little effect by itself but activates the effect of the thermostable component. The thermostable activating component is identical with 1‐tyrosine which is found in the liver extracts.