<tex-math>${}^{46}{\rm Scandium}$</tex-math> Metabolism; Binding to Metalloproteins in Vivo and in Vitro

Following the injection of rabbits with <tex-math>${}^{46}{\rm Sc}$</tex-math> as 1:2 citrate complex, the binding of scandium to metalloproteins and erythrocytes was studied. Binding to erythrocytes reached a peak after three days and thereafter declined with the plasma radioactivity level. This peak was not due to binding to haem as no incorporation into isolated haemin was observed. Scandium was shown to be transferred between transferrin and ferritin in vitro although in vivo the binding to ferritin appeared to be negligible compared with some other transition metals. The excretion of <tex-math>${}^{46}{\rm Sc}$</tex-math> in bile was studied using polyacrylamide gel electrophoresis. No specific scandium-protein complexes were observed, radioactivity being associated either with the bile pigments, or precipitated at the start of the gels or else associated with the small amount of transferrin naturally excreted in the bile.