Loss of chromium(III) from mixed Cr(III),Fe(III) serum Transferrins.

Trivalent chromium has been shown to be transported in vivo from the bloodstream to the tissues via endocytosis by transferrin (Tf), the major iron transport protein in the blood. Recent in vitro studies using Cr(III)-Tf have shown that under physiologically relevant conditions, the binding of Cr(III) to Tf and the loss of Cr(III) from the Cr(III)-Tf/Tf receptor complex are rapid. However, the major form of transferrin in the bloodstream is monoferric Tf.

Binding Chromium(III) to Form Mixed Cr(III),Fe(III) Serum Transferrins.

Transferrin, Tf, the protein that transports iron as Fe(III) from the blood to the tissues via endocytosis, is believed to also transport Cr(III). Under physiological conditions, Tf binds and releases Cr(III) rapidly from Cr(III)-Tf; however, the major form of Tf in the bloodstream is mono-ferric Tf (Fe(III)-Tf). Given the low concentration of Cr(III) in the bloodstream, the form of Cr(III)-containing Tf that is transported is probably monochromic, monoferric-Tf (Cr(III),Fe(III)-Tf).