Extracellular α-Galactosidase from Debaryomyces hansenii UFV-1 and Its Use in the Hydrolysis of Raffinose Oligosaccharides

Raffinose oligosaccharides (RO) are the factors primarily responsible for flatulence upon ingestion of soybean-derived products. ROs are hydrolyzed by α-galactosidases that cleave α-1,6-linkages of α-galactoside residues. The objectives of this study were the purification and characterization of extracellular α-galactosidase from Debaryomyces hansenii UFV-1. The enzyme purified by gel filtration and anion exchange chromatographies presented an M r value of 60 kDa and the N-terminal amino acid sequence YENGLNLVPQMGWN. The K m values for hydrolysis of pNPαGal, melibiose, stachyose, and raffinose were 0.30, 2.01, 9.66, and 16 mM, respectively. The α-galactosidase presented absolute specificity for galactose in the α-position, hydrolyzing pNPGal, stachyose, raffinose, melibiose, and polymers. The enzyme was noncompetitively inhibited by galactose (K i = 2.7 mM) and melibiose (K i = 1.2 mM). Enzyme treatments of soy milk for 4 h at 60 °C reduced the amounts of stachyose and raffinose by 100%. Keywords: α-Galactosidase; Debaryomyces hansenii UFV-1; raffinose oligosaccharides; characterization; flatulence