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.

A Fungal Alpha-Galactosidase from Pseudobalsamia microspora Capable of Degrading Raffinose Family Oligosaccharides

“…5 Thin-layer chromatography of the hydrolysis of raffinose and stachyose by alpha-galactosidase from Pseudobalsamia microspora: a enzymatically treated stachyose; b enzymatically treated raffinose substrate pNPGal, the enzyme exhibited lower activity for natural substrates such as melibiose (15.4 %), stachyose (6.4 %), and raffinose (49.9 %). Generally, alpha-galactosidase showed higher activity for composite substrates than natural substrates, consistent with the findings of Ferreira et al [25].…”

Multiple α-galactosidases from Aspergillus foetidus ZU-G1: purification, characterization and application in soybean milk hydrolysis

“…For -gal II, melibiose and stachyose showed best aYnity than raYnose. The K m values determined for pNPG were not all lower than natural substrates, such as raYnose, meliboise and stachyose, and the results were diVer with other reports [1,30]. From V max /K m values, we can see the catalytic power of -gal I, -gal II and -gal III to raYnose was few diVerence and the same to pNPG.…”

“…E1 could be a homopentamer, while E2 is a monomer in its native form. The native molecular mass of E3 was 51.7 kDa [1]. Thermomyces lanuginosus, Debaryomyces hansenii and Pleorotus Xorida are monomeric proteins with 57, 60 and 99 kDa, respectively [21][22][23].…”

“…However, soybean as well as other legumes characteristically contains high concentrations of the -galacto-oligosaccharides stachyose and raYnose [1], which are responsible for Xatulence upon ingestion of soybean-derived products and considered anti-nutritional factors for human and monogastric animals. Human digestive tract lacks -galactosidase, which is essential for the hydrolysis of these oligosaccharides.…”

“…-Galactosidase occurs widely in microorganisms, plants and animals, and Aspergillus has been shown to be a potential source of -galactosidase [1,[6][7][8], but biochemical and hydrolytic properties of -galactosidase were distinct from diVerent source. There are several reports available in the literature of the use of -galactosidase from plant and fungal sources for the removal of raYnose family sugars from soybean Xour and soybean milk [9][10][11].…”