Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa, 36.570-000 Viçosa, Minas Gerais, Brazil.
Appl Biochem Biotechnol. 2011 Aug;164(7):1111-25. doi: 10.1007/s12010-011-9198-y. Epub 2011 Feb 18.
α-Galactosidases has the potential to hydrolyze α-1-6 linkages in raffinose family oligosaccharides (RFO). Aspergillus terreus cells cultivated on wheat bran produced three extracellular forms of α-galactosidases (E1, E2, and E3). E1 and E2 α-galactosidases presented maximal activities at pH 5, while E3 α-galactosidase was more active at pH 5.5. The E1 and E2 enzymes showed stability for 6 h at pH 4-7. Maximal activities were determined at 60, 55, and 50 °C, for E1, E2, and E3 α-galactosidase, respectively. E2 α-galactosidase retained 90% of its initial activity after 70 h at 50 °C. The enzymes hydrolyzed ρNPGal, melibiose, raffinose and stachyose, and E1 and E2 enzymes were able to hydrolyze guar gum and locust bean gum substrates. E1 and E3 α-galactosidases were completely inhibited by Hg²⁺, Ag⁺, and Cu²⁺. The treatment of RFO present in soy milk with the enzymes showed that E1 α-galactosidase reduced the stachyose content to zero after 12 h of reaction, while E2 promoted total hydrolysis of raffinose. The complete removal of the oligosaccharides in soy milk could be reached by synergistic action of both enzymes.
α-半乳糖苷酶具有水解棉子糖家族低聚糖（RFO）中α-1-6 键的潜力。在麦麸上培养的土曲霉细胞产生了三种细胞外形式的α-半乳糖苷酶（E1、E2 和 E3）。E1 和 E2 α-半乳糖苷酶在 pH5 时表现出最大活性，而 E3 α-半乳糖苷酶在 pH5.5 时更活跃。E1 和 E2 酶在 pH4-7 下稳定 6 小时。E1、E2 和 E3 α-半乳糖苷酶的最大活性分别在 60、55 和 50°C 下确定。E2 α-半乳糖苷酶在 50°C 下 70 小时后保留了初始活性的 90%。这些酶水解 ρNPGal、蜜二糖、棉子糖和水苏糖，E1 和 E2 酶能够水解瓜尔胶和刺槐豆胶底物。E1 和 E3 α-半乳糖苷酶被 Hg²⁺、Ag⁺和 Cu²⁺完全抑制。用酶处理豆浆中存在的 RFO 表明，E1 α-半乳糖苷酶在 12 小时的反应后将水苏糖含量降低到零，而 E2 则促进了棉子糖的完全水解。通过两种酶的协同作用，可以达到豆浆中低聚糖的完全去除。
