Molecular Weights of Vitamin B₁₂Binding Proteins in Human Serum Determined by Sephadex G-200 Gel Filtration

Abstract

The molecular weights of the two principal vitamin B12 binding proteins in human serum, transcobalamin I and II, were estimated by gel filtration on Sephadex G-200 by the use of the correlation between the clution volume and the logarithm of the molecular weight of reference proteins. Mean values of 121,000 for transcobalamin I and 38,000 for transcobalamin II were obtained.