Interaction of albumin, transferrin, and human serum with indium-113 m complexes of ethylenediaminetetraacetic acid, penicillamine, and related compounds.

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Abstract
The interaction between the In complexes and human serum proteins was investigated by electrophoresis and gel filtration. Excess In above serum transferrin level bound to albumin and .alpha.1-globulins bound to transferrin. The sulfhydryl-containing ligands and EDTA prevented the In binding by albumin, in contrast with common amino acids. The In complexes of penicillamine, 2,3-dithiopropanol (BAL), and EDTA resist the transfer of In from the complexes to transferrin and the ability is related to the stability of the complexes, and to the molecular form and size of the ligands. Thioglycolic acid which prevents the hydrolysis of In and forms the In-transferrin-thioglycolate ternary complex, is available for the effective preparation of 113mIn- or 111In-transferrin. The binding-affinity of In(III) to ovotransferrin was approximately equal to that of Fe(III). The In complex of EDTA was present in the form of the dimer at the physiological pH, as well as the ferric complex. Based on these results, the usefulness of the inert In complexes of EDTA, penicillamine, BAL and the disulfhydryl-containing peptides as imaging agents, was discussed.