title: Beta-D-xylosidase from Selenomonas ruminantium of glycoside hydrolase family 43.
abstract: Beta-D-xylosidase from the ruminal anaerobic bacterium, Selenomonas ruminantium (SXA), catalyzes hydrolysis of beta-1,4-xylooligosacharides and has potential utility in saccharification processes. The enzyme, heterologously produced in Escherichia coli and purified to homogeneity, has an isoelectric point of approx 4.4, an intact N terminus, and a Stokes radius that defines a homotetramer. SXA denatures between pH 4.0 and 4.3 at 25 degrees C and between 50 and 60 degrees C at pH 5.3. Following heat or acid treatment, partially inactivated SXA exhibits lower k(cat) values, but similar K(m) values as untreated SXA. D-glucose and D-xylose protect SXA from inactivation at high temperature and low pH.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Fermentation Biotechnology Research Unit, National Center For Agricultural Utilization Research, 1815 N. University Street, Peoria, IL 61604, USA. jordand@ncaur.usda.gov
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Jordan
authors.forename: Xin-Liang
authors.initials: XL
authors.lastname: Li
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Dunlap
authors.forename: Terence R
authors.initials: TR
authors.lastname: Whitehead
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cotta
mesh_terms: D004789:Enzyme Activation; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry*; D020357:Selenomonas / Q000145:classification* / Q000201:enzymology*; D013045:Species Specificity; D013379:Substrate Specificity; D014995:Xylosidases / Q000737:chemistry*
chemical_list: D006026:Glycoside Hydrolases; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase