Dey P M, Pridham J B
Biochem J. 1969 Jun;113(1):49-55. doi: 10.1042/bj1130049.
Two forms of alpha-galactosidase, I and II, exist in Vicia faba seeds and these have been purified 3660- and 337-fold respectively. They behaved as homogeneous preparations when examined by ultracentrifugation, disc electrophoresis and gel filtration. The apparent molecular weights of enzymes I and II, as determined by gel filtration, were 209000 and 38000 respectively. The carbohydrate contents of enzymes I and II were 25% and 2.8% respectively, and the enzymes differed in their aromatic amino acid compositions. Enzyme I was split into six inactive subunits in the presence of 6m-urea. alpha-Galactosidases I and II showed different pH optima and K(m) and V(max.) values with p-nitrophenyl alpha-d-galactoside and raffinose as substrates, and also differed in their thermal stabilities.
蚕豆种子中存在两种形式的α-半乳糖苷酶，即I型和II型，它们分别被纯化了3660倍和337倍。通过超速离心、圆盘电泳和凝胶过滤检测时，它们表现为均一的制剂。通过凝胶过滤测定，酶I和酶II的表观分子量分别为209000和38000。酶I和酶II的碳水化合物含量分别为25%和2.8%，并且这两种酶的芳香族氨基酸组成不同。在6m尿素存在的情况下，酶I被裂解为六个无活性的亚基。以对硝基苯基α-D-半乳糖苷和棉子糖为底物时，α-半乳糖苷酶I和II表现出不同的最适pH值、米氏常数（K(m)）和最大反应速度（V(max.)）值，并且它们的热稳定性也不同。
