Purification and characterization of a thermostable α-galactosidase from Thermoanaerobacterium polysaccharolyticum

Michael R. King, Bryan A White, Hans P. Blaschek, Bruce M. Chassy, Roderick I. Mackie, Isaac K.O. Cann

Research output: Contribution to journalArticlepeer-review


Food ingredients containing α-1,6-galactoside bonds elicit gastrointestinal disturbances in monogastric animals, including humans. Pretreatment of such ingredients with α-galactosidase (EC has the potential to alleviate this condition. For this purpose, a thermostable α-galactosidase from Thermoanaerobacterium polysaccharolyticum was purified by a combination of anion exchange and size exclusion chromatographies. The enzyme has a monomeric molecular weight of ∼80 kDa; however, it is active as a dimer. The optimum temperature for enzyme activity is 77.5 °C. Approximately 84 and 88% of enzyme activity remained after 36.5 h of incubation at 70 and 65 °C, respectively. Optimum activity was observed at pH 8.0, with a broad range of activity from pH 5.0 to 9.0. Different transition metals had weak to strong inhibitory effects on enzyme activity. The Km and Vmax of the enzyme are 0.29-0.345 mM and 200-232 μmol/min/mg of protein, respectively. Importantly, enzyme activity was only slightly inhibited by 75-100 mM galactose, an end product of hydrolysis. Enzyme activity was specific for the α-1,6-galactosyl bond, and activity was demonstrated on melibiose and soy molasses.

Original languageEnglish (US)
Pages (from-to)5676-5682
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Issue number20
StatePublished - Sep 25 2002


  • Purification
  • Thermoanaerobacterium polysaccharolyticum
  • Thermostability
  • α-galactosidase

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)


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