Etude de Deux Transporteurs de Vitamine B12 Isolés de la Muqueuse Gastrique de Porc

Summary An extract from hog gastric mucosa is fractioned through salting out with ammonium sulfate, chromatography on DEAE-Sephadex A 50 and filtration on a column of Sephadex G 100 in acetic acid 0·1 M. Continuous free-flow high-voltage electrophoresis allows the separation of two gastric vitamin B 12 binders with sedimentation constants S 20 ° = 2–8 and S 20 ° = 1·12. These preparations are compared to the intrinsic factor isolated through the Ellenbogen and Highley process. They possess the same antigenic determinant specific of the organ and a high binding affinity for cyanocobalamin. We have focused our attention on these two preparations to get information about the structural features accompanying the binding power. Histidin alleviation, lysin ɛNH 2 groups succinylation, carboxylic groups esterification and the breaking of alkali-sensitive linkages do not alter the binding power towards the vitamin B 12 . Disulfur bridges reduction followed by alkylation by iodoacetamid destroys a great part of the binding activity. The blockage of guanidic groups of arginin by 1,2-cyclohexanedione is sufficient to suppress altogether the affinity of the binders towards B 12 vitamin.