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 alpha-galactosidases that cleave alpha-1,6-linkages of a-galactoside residues. The objectives of this study were the purification and characterization of extracellular alpha-galactosidase from Debatyomyces 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 pNP alpha Gal, melibiose, stachyose, and raffinose were 0.30, 2.01, 9.66, and 16 mM, respectively. The alpha-galactosidase presented absolute specificity for galactose in the alpha-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 degrees C reduced the amounts of stachyose and raffinose by 100%.