Deposition of dietary organic and inorganic selenium in rat erythrocyte proteins.

The deposition of selenium (Se) in erythrocyte proteins was studied in rats fed Se as sodium selenite, selenocystine, selenomethionine (Se-Met), high Se wheat or selenium-enriched yeast. Ion-exchange chromatography of acid hydrolyzates of selenium-enriched yeast, high Se wheat and intrinsically labeled 75Se wheat indicated that the majority of the Se was present as Se-Met. Gel filtration (Sephadex G-150) of erythrocyte lysates revealed that Se was deposited mainly in two proteins, glutathione peroxidase (GPx) and hemoglobin (Hb). When selenite or selenocystine was the dietary form of Se, the majority of the erythrocyte Se was present with GPx, but when the Se was supplied from either Se-Met, yeast or wheat, it was deposited to a greater extent in Hb than GPx. Injection of 75Se as either Se-Met or selenite gave results consistent with the feeding studies. 75Se-labeled selenite injection resulted in labeling of primarily GPx, but 75Se-Met injection labeled predominantly Hb. Hence, the dietary forms of Se influence the relative distribution of Se between GPx and Hb in erythrocytes, and this may be a factor contributing to the difference between human and animal erythrocytes.