title: Purification and characterization of Aspergillus terreus α-galactosidases and their use for hydrolysis of soymilk oligosaccharides.
abstract: 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.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa, 36.570-000 Viçosa, Minas Gerais, Brazil.
authors.forename: Joana Gasperazzo
authors.initials: JG
authors.lastname: Ferreira
authors.forename: Angélica Pataro
authors.initials: AP
authors.lastname: Reis
authors.forename: Valéria Monteze
authors.initials: VM
authors.lastname: Guimarães
authors.forename: Daniel Luciano
authors.initials: DL
authors.lastname: Falkoski
authors.forename: Lílian da Silva
authors.initials: Lda S
authors.lastname: Fialho
authors.forename: Sebastião Tavares
authors.initials: ST
authors.lastname: de Rezende
mesh_terms: D001230:Aspergillus / Q000737:chemistry / Q000201:enzymology*; D004043:Dietary Fiber / Q000378:metabolism; D004415:Dyspepsia / Q000517:prevention & control; D004795:Enzyme Stability; D005511:Food Handling / Q000379:methods*; D005685:Galactans / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D008351:Mannans / Q000378:metabolism; D008553:Melibiose / Q000378:metabolism; D019216:Metals, Heavy / Q000494:pharmacology; D009844:Oligosaccharides / Q000378:metabolism; D053149:Plant Gums / Q000378:metabolism; D011887:Raffinose / Q000378:metabolism; D041942:Soy Milk / Q000737:chemistry / Q000378:metabolism*; D013025:Glycine max / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature; D000519:alpha-Galactosidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004043:Dietary Fiber; D005685:Galactans; D008351:Mannans; D019216:Metals, Heavy; D009844:Oligosaccharides; D053149:Plant Gums; C005695:stachyose; D008553:Melibiose; C007894:guar gum; D000519:alpha-Galactosidase; D011887:Raffinose; C017471:locust bean gum