title: Acid xylanase from yeast Cryptococcus sp. S-2: purification, characterization, cloning, and sequencing.
abstract: A xylan-degrading enzyme produced by yeast Cryptococcus sp. S-2 was isolated and purified, and characterized as an endoxylanase (1,4-beta-D-xylan xylanohydrolase [EC 3.2.1.8]). We estimated the molecular weight and isoelectric point of purified xylanase (xyn-CS2) to be 22,000 and 7.4, respectively. This low-molecular-weight xylanase had an unusual pH optimum of 2.0, and showed 75% of maximal activity even at pH 1.0. An open reading frame of the cDNA specified 209 amino acids, including a putative signal peptide of 25 amino acids. The deduced amino acid sequence of xyn-CS2 shared significant similarities with the family-G xylanases of B. pumilus, C. acetobutylicum, T. reesei, and A. kawachii. Xyn-CS2 included two unique cysteine residues in a putative catalytic region, raising the possibility that these residues are at least partially responsible for its acidophilic nature.
authors.affiliation: National Research Institute of Brewing, Higashi-hiroshima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iefuji
authors.forename: M
authors.initials: M
authors.lastname: Chino
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Iimura
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003454:Cryptococcus / Q000201:enzymology*; D018076:DNA, Complementary / Q000302:isolation & purification; D004795:Enzyme Stability; D005815:Genetic Code; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D018076:DNA, Complementary; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase