Fractionation of Soluble Molybdenum-Binding Proteins from Liver,Kidney, Plasma and Erythrocytes from Sheep Supplemented with Molybdenum

Five ewes were given a daily dose of 1.4 mg Mo/kg body weight as ammonium molybdate for 21 to 55 days. Plasma molybdenum concentrations increased considerably following the dosage, but no systematic changes were seen in the plasma copper concentrations. About 80 % of the molybdenum present in blood was found in plasma. With gel filtration it was shown that practically all of the molybdenum present in plasma and red cell haemolyzates was found in a fraction with molecular weight less than 1,500. Soluble proteins from liver and kidney cortex were separated into one high molecular weight fraction with molecular weight above 200,000 and a non-protein fraction with molecular weight less than 1,500. Significant correlations were found between the amounts of molybdenum present in the high molecular weight fraction and the molybdenum concentrations in liver and kidney.