Purification and characterization of a maltase from the extremely thermophilic crenarchaeote Sulfolobus solfataricus

A soluble maltase (alpha-glucosidase) with an apparent subunit mass of 80 kDa was purified to homogeneity from Sulfolobus solfataricus. The enzyme liberates glucose from maltose and malto-oligomers. Maximal activity was observed at 105 degrees C, with half-lives of 11 h (85 degrees C), 3.0 h (95 degrees C), and 2.75 h (100 degrees C). The enzyme was generally resistant to proteolysis and denaturants including aliphatic alcohols. n-Propanol treatment at 85 degrees C increased both Km and Vmax for maltose hydrolysis.