Low molecular weight iron from guinea pig reticulocytes isolated by Sephadex G‐25 chromatography

As part of a continuing study of the low MW iron pool, guinea pig reticulocytes were incubated with ⁵⁹Fe‐labeled transferrin, and the reticulocyte hemolysate was chromatographed on Sephadex G‐25. ⁵⁹Fe, in amounts corresponding to that which was in a low MW peak eluting from an Ultrogel column and to that not precipitated by ammonium sulfate, adsorbed to the Sephadex column. The adsorbing ⁵⁹Fe, on elution from the Sephadex with dilute formic acid, coeluted with phosphate and pentose. When EDTA was added to disrupt the putative iron complex, neither iron nor P adsorbed to the column, supporting the argument that they exist as a compound in the cytosol and adsorb and elute together for that reason. These observations provide additional evidence that P‐containing compounds, probably originating as nucleotides, are important components of the low MW iron pool of cells.