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

A soluble maltase (α-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°C, with half-lives of 11 h (85°C), 3.0 h (95°C), and 2.75 h (100°C). The enzyme was generally resistant to proteolysis and denaturants including aliphatic alcohols. n-Propanol treatment at 85°C increased both K(m) and V(max) for maltose hydrolysis.