Degradation of flatulence-causing oligosaccharides in soymilk by α-galactosidase—A novel thermotolerant from <i style="">Penicillium purpurogenum</i>

Abstract

α-Galactosidase from <i style="">Penicillium purpurogenum</i> was induced to a greater extent in the culture medium by arabinose, galactose, lactose and guar galactomannan. The enzyme was purified by acetone precipitation and DEAE-Sephacel column chromatography. The purified enzyme showed a single band in both native-PAGE and SDS-PAGE. The molecular mass of enzyme was found to be between 107 and 110 kDa. The enzyme exhibited the optimum <i>p</i>H and temperature at 5.0 and 55ºC, respectively. α-Galactosidase was strongly inhibited by Ag⁺ and Hg²⁺, while Fe²⁺ enhanced the activity. PMSF did not inhibit α-galactosidase activity, whereas N-bromosuccinimide completely inhibited the enzyme activity. Further, galactose and melibiose moderately inhibited the enzyme activity. The K_m values for PNPG, melibiose, raffinose and stachyose were found to be 0.20, 5.26, 10 and 9.1, respectively. α-Galactosidase completely hydrolyzed flatulence-causing raffinose and stachyose of soymilk in 1.45 h.