α‐D‐Galactosidase from Soybeans Destroying Blood‐Group B Antigens

Abstract

α-D-Galactosidase was isolated from untoasted soybean meal and purified to homogeneity by affinity chromatography on N-ɛ-aminoacaproyl α-D-galactopyranosylamine-Sepharose. The purified enzyme destroyed the B-specificity of human ovarian cyst B-glycoprotein with an accompanying increase in H-specificity, and converted human type-B erythrocytes to type O. The enzyme consists primarily of a tetramer, molecular weight 150000 ± 5000 at pH 4.0, and of a monomer, molecular weight 40000 ± 3000 at pH 8.0. Polyacrylamide gel electrophoresis in dodecyl sulfate at pH 7.2 distinguished between two types of monomeric unit of similar molecular weight. N-terminal alanine was identified as the sole N-terminal amino acid residue. The enzyme was shown to be devoid of carbohydrate.