title: Thermostable beta-glucosidase and beta-xylosidase from Thermotoga sp. strain FjSS3-B.1.
abstract: A beta-D-glucosidase and a beta-D-xylosidase were purified to homogeneity from the thermophilic eubacterium Thermotoga sp. strain FjSS3-B.1. Both enzymes were largely cell-associated and were probably associated with the 'toga' structures of this organism. Using SDS-PAGE they were found to have M(r) values of 75,000 and 92,000, respectively. The beta-glucosidase was active against cellobiose, sophorose and gentiobiose with Km values of 59 mM, 2.7 mM and 6 mM, respectively. The beta-xylosidase had a Km of 2 mM for xylobiose, showed strong activity against p-nitrophenyl alpha-L-arabinofuranoside and p-nitrophenyl alpha-L-arabinopyranoside, but was subject to strong substrate inhibition by p-nitrophenyl beta-D-xylopyranoside. Both enzymes were extremely thermostable, with half-lives of several hours at 98 degrees C. The thermostabilities of both enzymes were increased further by the addition of either trehalose or betaine.
authors.affiliation: Thermophile Research Unit, School of Science and Technology, University of Waikato, Hamilton, New Zealand.
authors.forename: L D
authors.initials: LD
authors.lastname: Ruttersmith
authors.forename: R M
authors.initials: RM
authors.lastname: Daniel
mesh_terms: D001622:Betaine / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D006089:Gram-Negative Anaerobic Bacteria / Q000201:enzymology* / Q000235:genetics; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013379:Substrate Specificity; D014199:Trehalose / Q000494:pharmacology; D014995:Xylosidases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D001617:beta-Glucosidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D001622:Betaine; D014199:Trehalose; D006026:Glycoside Hydrolases; D014995:Xylosidases; D001617:beta-Glucosidase; C026579:exo-1,4-beta-D-xylosidase; C019713:alpha-N-arabinofuranosidase