International Journal of Molecular Sciences, Vol.16, No.12, 29226-29235, 2015
Hydrolysis of Oligosaccharides by a Thermostable alpha-Galactosidase from Termitomyces eurrhizus
The genus of Termitomyces purchased from the market has been identified as Termitomyces eurrhizus using the Internal Transcribed Spacer (ITS) method. An -galactosidase from T. eurrhizus (TEG), a monomeric protein with a molecular mass of 72 kDa, was purified 146 fold by employing ion exchange chromatography and gel filtration. The optimum pH and temperature was 5.0 and 60 degrees C, respectively. TEG was stable over pH 2-6, and also exhibited good thermostablility, retaining 100% of the original activity after incubation at 60 degrees C for 2 h. Inhibition of the enzyme activity by N-bromosuccinimide (NBS) constituted evidence for an essential role of tryptophan in the catalytic action of the isolated enzyme. Besides 4-nitro-phenyl -d-galactophyranoside (pNPGal), natural substrates could also be effectively hydrolyzed by TEG. Results of thin-layer chromatography (TLC) revealed complete enzymatic hydrolysis of raffinose and stachyose to galactose at 50 degrees C within 6 h. These properties of TEG advocate its utilization for elevating the nutritional value of soymilk.