A cell-associated oligo-1,6-α-glucosidase from an extremely thermophilic anaerobic bacterium, Thermoanaerobium Tok6-B1

Abstract

Cell-associated oligo-1,6-alpha-glucosidase (EC 3.2.1.10) was isolated from Thermoanaerobium Tok6-B1 grown on starch-containing medium. Activity was purified 11.4-fold by salt precipitation, gel filtration, hydroxyapatite and anion-exchange chromatography. Molecular mass was determined as 30,000 by SDS/polyacrylamide-gel electrophoresis and 33,000 by analytical gel filtration. The probable order of specificity was p-nitrophenyl-alpha D-glucose greater than-isomaltose greater than-isomaltotriose greater than-panose greater than-nigerose and no activity was shown against malto-oligosaccharides, melezitose, melibiose, raffinose, cellobiose, sophorose, gentiobiose, lactose, pullulan, dextran or amylose. The optima for activity and stability were between pH 5.6 and 7.0 and the half-life at pH 6.5 was 1000 min at 70 degrees C and 20 min at 76 degrees C. Activity was stabilized by substrate, Mg2+, Mn2+ and Ca2+, but was destabilized by Zn2+ and EDTA. N-Ethylmaleimide, glucose and 1-O-methyl-alpha D-glucose were inhibitory but 1-O-methyl-beta D-glucose stimulated activity. The activation energy (Ea) was 109 kJ/mol.

Limited proteolysis as a probe of conformational changes in aspartate aminotransferase from Sulfolobus solfataricus

“…The trend of the k,,, Arrhenius plot is not peculiar to AspATSs but is observed for many thermophilic enzymes, although the temperature at which the discontinuity occurs differs (see, for example, the cases described by Bryant and Adams, 1989;Cocco et al, 1988;Ferracin et al, 1989;Fusek et al, 1990;Hecht et al, 1989;Livingston et al, 1987;Plant et al, 1988;Sugimoto and Nosoh, 1971;Wrba et al, 1990).…”

Microbial Enzymes and Biotechnology

“…cereus (Suzuki et al, 1982); B. KP1071 and Thermoanaerobium Tok 6-B1 (Plant et al, 1988). KP1071 and Thermoanaerobium Tok 6-B1 (Plant et al, 1988).…”

Properties and stabilization of an extracellular α-glucosidase from the extremely thermophilic archaebacteria Thermococcus strain AN 1: enzyme activity at 130°C

“…1.20) and oligo-1,6 α-glucosidase (EC 3.2.1.10) [3]. The α-glucosidase described here is from Thermococcus strain AN1, an extremely thermophilic, sulphur reducing archaebacterium which was isolated from a geothermal spring in Rotorua, New Zealand [4,5].…”