title: Novel substrate specificity of a membrane-bound beta-glycosidase from the hyperthermophilic archaeon Pyrococcus horikoshii.
abstract: A beta-glycosidase gene homolog of Pyrococcus horikoshii (BGPh) was successfully expressed in Escherichia coli. The enzyme was localized in a membrane fraction and solubilized with 2.5% Triton X-100 at 85 degrees C for 15 min. The optimum pH was 6.0 and the optimum temperature was over 100 degrees C, respectively. BGPh stability was dependent on the presence of Triton X-100, the enzyme's half-life at 90 degrees C (pH 6.0) was 15 h. BGPh has a novel substrate specificity with k(cat)/K(m) values high enough for hydrolysis of beta-D-Glcp derivatives with long alkyl chain at the reducing end and low enough for the hydrolysis of beta-linked glucose dimer more hydrophilic than aryl- or alkyl-beta-D-Glcp.
authors.affiliation: National Institute of Bioscience and Human-Technology, Tsukuba, Ibaraki, Japan. ikmatsui@nibh.go.jp
authors.forename: I
authors.initials: I
authors.lastname: Matsui
authors.forename: Y
authors.initials: Y
authors.lastname: Sakai
authors.forename: E
authors.initials: E
authors.lastname: Matsui
authors.forename: H
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Kawarabayasi
authors.forename: K
authors.initials: K
authors.lastname: Honda
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005962:Glucosylceramidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019711:Pyrococcus / Q000201:enzymology*; D016415:Sequence Alignment; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D008565:Membrane Proteins; D005962:Glucosylceramidase