title: Endo-1,4-beta-xylanase B from Aspergillus cf. niger BCC14405 isolated in Thailand: purification, characterization and gene isolation.
abstract: During the screening of xylanolytic enzymes from locally isolated fungi, one strain BCC14405, exhibited high enzyme activity with thermostability. This fugal strain was identified as Aspergillus cf. niger based on its morphological characteristics and internal transcribed spacer (ITS) sequences. An enzyme with xylanolytic activity from BCC14405 was later purified and characterized. It was found to have a molecular mass of ca. 21 kDa, an optimal pH of 5.0, and an optimal temperature of 55 degrees C. When tested using xylan from birchwood, it showed K(m) and V(max) values of 8.9 mg/ml and 11,100 U/mg, respectively. The enzyme was inhibited by CuSO(4) EDTA, and by FeSO(4) The homology of the 20-residue N-terminal protein sequence showed that the enzyme was an endo-1,4-beta-xylanase. The full-length gene encoding endo-1,4-beta-xylanase from BCC14405 was obtained by PCR amplification of its cDNA. The gene contained an open reading frame of 678 bp, encoding a 225 amino acid protein, which was identical to the endo-1,4-a-xylanase B previously identified in A. niger.
authors.affiliation: National Center for Genetic Engineering and Biotechnology,113 Thailand Science Park, Paholyothin Rd., Klong 1, Klong Luang, Pathumthani 12120, Thailand. krisanap@hotmail.com
authors.forename: Asano
authors.initials: A
authors.lastname: Krisana
authors.forename: Sriprang
authors.initials: S
authors.lastname: Rutchadaporn
authors.forename: Gobsuk
authors.initials: G
authors.lastname: Jarupan
authors.forename: Eurwilaichitr
authors.initials: E
authors.lastname: Lily
authors.forename: Tanapongpipat
authors.initials: T
authors.lastname: Sutipa
authors.forename: Kirtikara
authors.initials: K
authors.lastname: Kanyawim
mesh_terms: D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology*; D001483:Base Sequence; D029662:Betula; D003001:Cloning, Molecular; D019327:Copper Sulfate / Q000494:pharmacology; D018076:DNA, Complementary; D004492:Edetic Acid / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D013379:Substrate Specificity; D013785:Thailand; D014990:Xylans / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D014990:Xylans; D004492:Edetic Acid; D043364:Endo-1,4-beta Xylanases; D019327:Copper Sulfate