Effect of dietary Mo on Cu metabolism. Evidence for the involvement of Mo in abnormal binding of Cu to plasma proteins.

The effects of feeding Mo at concentrations of 17 mug/g to sheep and 100 mug/g to guinea pigs in the presence of adequate dietary Cu, on the distribution of Cu within plasma have been studied. The creation of a fraction of plasma Cu which is insoluble in trichloroacetic acid has been confirmed and it has been shown that this fraction also contains Mo. Complete removal of Cu and Mo from this protein cannot be achieved under acid conditions without at least partial hydrolysis of the protein. The estimated atomic ratio of Cu:Mo in the fraction was 1.7. It is suggested that the formation of such a stable Cu-Mo-protein compound may explain the observed low tissue uptake of Cu in the presence of high plasma total and "direct-reacting" Cu concentrations.