Abstract
Summary
Studies were performed to determine the effects of liver homogenates and subcellular fractions on the inactivation of ESF. ESF was assayed using the percentage of 59Fe incorporation into the erythrocytes of exhypoxic polycythemic mice. Liver inactivation of ESF was found to correlate with the activity of β-glucuronidase, a lysosomal marker enzyme. Incubation of ESF with hepatic lysosomal fractions resulted in a reduction in erythropoietic activity which was significant after 15 min. Further progressive inactivation occurred over a period of 6 hr. Decreasing the content of the lysosomal protein in the reaction flasks or heat denaturation of the lysosomal fraction substantially reduced the amount of ESF inactivation, providing additional evidence that this process is enzymatic.
The authors acknowledge the excellent technical assistance of Mr. Jesse Brookins, Mr. Rene Stiaes and Miss Pat Dargon.
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