Chemical and Biological Properties of Fractions Derived from Hog Intrinsic Factor Concentrate by Disc Electrophoresis. ∗

Abstract

Summary

HIFC was separated by polysaccharide disc electrophoresis into a distinct polysaccharide fraction (F-II), and 3 distinct protein fractions. Disc electrophoresis of the HIFC complexed with isotopically labelled vit B12 revealed that only one of these fractions (F-III), a protein devoid of stain-able polysaccharide, bound B₁₂ avidly. When the losses due to processing are considered. F-III represents approximately 80% of the binding activity in the starting material. Following elution, F-III shows intrinsic factor activity by in vitro (guinea pig intestinal mu-cosal homogenate method) bioassay, and in vivo by Schilling's method in a patient with pernicious anemia, All other fractions were inert in vitro. Thus a protein moiety, free of polysaccharide, was responsible for both B₁₂ binding and the specific enhancement of absorption. The sialic acid-containing major polysaccharide fraction (F-II) showed no significant B₁₂ or in vitro activity.