The iron transport protein transferrin (Tf) has been proposed to function as a detoxification agent for dietary Cr(III), carrying Cr from the blood to the tissues or ultimate release in the urine. Recently, however, the release of Cr(III) from Cr<sub>2</sub>-Tf metal has been proposed to be too slow for Cr(III) to be released during endocytosis]. Using CW-EPR, the loss of Cr(III) from Cr<sub>2</sub>-Tf over 24 hours at both pH 5.5 and 4.5 has been monitored. The effects of several biological relevant chelate ligands and EDTA on Cr loss have also been examined. Cr(III) was found to rapidly dissociate from the weak Cr(III) binding site of Tf at both pH’s regardless of which chelator was present, while loss from the tight binding site was appreciably slower. The rates of Cr(III) loss as a function of pH and chelator will be presented.

Rate of dissociation of chromium(III) from transferrin under endosomal conditions monitored by EPR

255th National Meeting (2018)

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