title: Characterization of beta-xylosidase enzyme from a Pichia stipitis mutant.
abstract: beta-Xylosidase production was maximal for the mutant Pichia stipitis NP54376 grown on xylan as the sole carbon source. beta-Xylosidase was purified from culture supernatant by (NH(4))(2)SO(4) precipitation and a hydrophobic interaction chromatography on phenyl sepharose. Optima of pH and temperature were 5.0 and 50 degrees C, respectively. The enzyme was inhibited by 2-mercaptoethanol (100%) and Fe(3+) (80%), and moderately affected by Cu(2+), Ag(+), NH(4)(+) and Mg(2+) and SDS. The purified xylosidase hydrolyzed xylobiose and xylo-oligosaccharides and it did not exhibit activity against cellulose, starch, maltose and cellobiose. 2.5 g l(-1) glucose repressed beta-xylosidase activity in the NP54376 strain. The K(m) and V(max) values on p-nitrophenyl-beta-xylopyranoside were 1.6 mM and 186 micromol p-nitrophenyl min(-1)mg(-1) protein, respectively. Analysis of the hydrolysis products by HPLC indicated that the major hydrolysis product is xylobiose in all the carbon sources tested.
authors.affiliation: Institute for Prospective Technological Studies, Joint Research Center, Seville, Spain. pervinb@ziraat.sdu.edu.tr
authors.forename: Pervin
authors.initials: P
authors.lastname: Basaran
authors.forename: Meltem
authors.initials: M
authors.lastname: Ozcan
mesh_terms: D000143:Acids / Q000494:pharmacology; D000596:Amino Acids / Q000032:analysis; D019149:Bioreactors; D018929:Cell Culture Techniques; D002845:Chromatography / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D004187:Disaccharides / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009154:Mutation; D009844:Oligosaccharides / Q000378:metabolism; D010843:Pichia / Q000201:enzymology* / Q000235:genetics*; D013696:Temperature; D014990:Xylans / Q000378:metabolism; D014995:Xylosidases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000143:Acids; D000596:Amino Acids; D004187:Disaccharides; D009844:Oligosaccharides; D014990:Xylans; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase; C004173:xylobiose; D005947:Glucose