The recognition of metallo-transferrin complexes (M2Tf) by the cognate transferrin receptor (TfR) is the critical step for cellular uptake of these metal ions. A high performance liquid chromatography-based method coupled to UV-Visible and luminescence spectroscopies was used to probe the binding of metal-bound M2Tf to the TfR, yielding a direct measurement of the successive thermodynamic constants that correspond to the dissociation of TfR:(M2Tf)2 and TfR:(M2Tf) adducts for transition metals, lanthanides, and alpha and neutron emitting actinides. Under the chosen experimental conditions, the respective stabilities of TfR:(MxTf)y adducts follow the order FeIII >>  ThIV ~ UVIO2 ~ CmIII >  LnIII ~ GaIII >>>  YbIII ~ PuIV. This study confirms the high selectivity of the Tf/TfR-mediated endocytosis pathway, which plays a major role in the translocation mechanisms of exogenous metal contaminants and could be exploited for the development of new separation technologies.

Transferrin-mediated endocytosis of metal ions: A highly selective process

245th National Meeting (2013)

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