title: A new thermostable alpha-L-arabinofuranosidase from a novel thermophilic bacterium.
abstract: An alpha-L-arabinofuranosidase gene was identified in a sequenced genome of a novel thermophilic bacterium, which belongs to the recently described phylum of Thermomicrobia. Amino acid sequence comparison of the enzyme (designated AraF) revealed similarity to glycoside hydrolases of family 51. The gene was cloned into Escherichia coli and its recombinant product expressed and purified. The enzyme appeared to be a hexamer. AraF was optimally active at 70 degrees C (over 10 min) and pH 6 having 92% residual activity after 1 h at 70 degrees C. AraF had a Km) value of 0.6 mM and V(max) value of 122 U mg(-1) on p-nitrophenyl-alpha-L-arabinofuranoside. AraF was almost equally active on branched arabinan and debranched arabinan, properties not previously found in alpha-L-arabinofuranosidases in GH family 51.
authors.affiliation: Prokaria Ltd., Gylfaflöt 5, 112 Reykjavik, Iceland. hakon.birgisson@prokaria.com
authors.forename: Hákon
authors.initials: H
authors.lastname: Birgisson
authors.forename: Olafur
authors.initials: O
authors.lastname: Fridjonsson
authors.forename: Farah Khadijeh
authors.initials: FK
authors.lastname: Bahrani-Mougeot
authors.forename: Gudmundur O
authors.initials: GO
authors.lastname: Hreggvidsson
authors.forename: Jakob K
authors.initials: JK
authors.lastname: Kristjansson
authors.forename: Bo
authors.initials: B
authors.lastname: Mattiasson
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D041862:Chloroflexi / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D015870:Gene Expression; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011134:Polysaccharides / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D011134:Polysaccharides; C030080:araban; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase