title: A novel type of thermostable alpha-D-glucosidase from Thermoanaerobacter thermohydrosulfuricus exhibiting maltodextrinohydrolase activity.
abstract: An alpha-glucosidase with the ability to attack polymeric substrates was purified to homogeneity from culture supernatants of Thermoanaerobacter thermohydrosulfuricus DSM 567. The enzyme is apparently a glycoprotein with a molecular mass of 160 kDa. Maximal activity is observed between pH5 and 7 at 75 degrees C. The alpha-glucosidase is active towards p-nitrophenyl-alpha-D-glucoside, maltose, malto-oligosaccharides, starch and pullulan. Highest activity is displayed towards the disaccharide maltose. In addition to glucose, maltohexaose and maltoheptaose can be detected as the initial products of starch hydrolysis. After short incubations of pullulan, glucose is found as the only product. At high substrate concentrations, maltose and malto-oligosaccharide, but not glucose, are used as acceptors for glucosyl-transfer. These findings indicate that the T. thermohydrosulfuricus enzyme represents a novel type of alpha-glucosidase exhibiting maltase, glucohydrolase and 'maltodextrinohydrolase' activity.
authors.affiliation: Institute for Microbiology, Technical University Munich, Arcisstrasse 21, D-80290 München, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Wimmer
authors.forename: F
authors.initials: F
authors.lastname: Lottspeich
authors.forename: J
authors.initials: J
authors.lastname: Ritter
authors.forename: K
authors.initials: K
authors.lastname: Bronnenmeier
mesh_terms: D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D004795:Enzyme Stability; D005936:Glucans / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D016988:Gram-Positive Asporogenous Rods, Irregular / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008954:Models, Biological; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D017421:Sequence Analysis; D013045:Species Specificity; D013213:Starch / Q000378:metabolism; D013379:Substrate Specificity; D000520:alpha-Glucosidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D005936:Glucans; D011134:Polysaccharides; C008315:maltodextrin; C009109:pullulan; D013213:Starch; D000520:alpha-Glucosidases; D005947:Glucose