The Biosynthesis of Blood‐Group‐B Character on Human O‐Erythrocytes by a Soluble α‐Galactosyltransferase from Milk

The enzyme α‐galactosyltransferase from human milk catalysed the synthesis of B‐character on blood‐group‐O erythrocytes. Erythrocytes from secretors and nonsecretors participated in this reaction to the same extent. Substances possessing H‐active structure inhibited the acquisition of B‐character by erythrocytes when added to the reaction mixture. The enzyme also incorporated galactose into isolated, water‐soluble substances of erythrocytes with H‐activity from secretors.