Concentration of Intrinsic Factor and Vitamin B₁₂-Binding Activities of Fractions of Desiccated Hog Stomach

Fractionation of desiccated defatted hog stomach through the use of isoelectric and ammonium sulfate precipitation technics, and guided by assays in patients with pernicious anemia in relapse given daily oral doses of 5 µg. of vitamin B₁₂, has led to the concentration of intrinsic factor activity in an amount of protein equivalent to 0.03 per cent of the original weight of crude material. The electrophoretic pattern of this active fraction indicated a lack of homogeneity.

The vitamin B₁₂-binding activities of three fractions obtained by precipitation with ammonium sulfate were investigated by microbial inhibition and dialysis methods. There was no correlation between the ability of the fractions to bind vitamin B₁₂ and to exert intrinsic factor activity. Among these fractions, that with the highest intrinsic factor activity in patients with pernicious anemia in relapse bound the least amount of vitamin B₁₂.