title: Agrobacterium tumefaciens beta-glucosidase is also an effective beta-xylosidase, and has a high transglycosylation activity in the presence of alcohols.
abstract: Agrobacterium tumefaciens beta-glucosidase, Cbg1 was extensively characterised and found to be a retaining aryl-glucosidase and an aryl-xylosidase. Cbg1s specificity for p-nitrophenyl beta-d-xylopyranoside was 73% that for p-nitrophenyl beta-d-glucopyranoside when measured by the ratio kcat/Km. The enzyme also hydrolysed p-nitrophenyl beta-d-fucopyranoside, and p-nitrophenyl beta-d-galactopyranoside with moderate efficiency. The enzyme released only terminal glucose from p-nitrophenyl beta-cellobioside and had a 20 000-fold preference for its natural substrate coniferin over cellobiose as indicated by the ratio kcat/Km. The enzyme was activated in the presence of 20 mM 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol. In the case of butanol this activation was investigated and shown to be due to transglycosylation activity with over 80% of p-nitrophenyl beta-d-glucopyranoside being converted to 1-butyl beta-d-glucopyranoside in the presence of Cbg1 and 100 mM 1-butanol.
authors.affiliation: Applied Enzymology Laboratory, National Food Research Institute, Tsukuba, Ibaraki 305, Japan.
authors.forename: D K
authors.initials: DK
authors.lastname: Watt
authors.forename: H
authors.initials: H
authors.lastname: Ono
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology* / Q000235:genetics; D000438:Alcohols / Q000494:pharmacology*; D002863:Chromogenic Compounds / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005960:Glucosides / Q000378:metabolism; D006031:Glycosylation; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D014995:Xylosidases / Q000378:metabolism*; D001617:beta-Glucosidase / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000438:Alcohols; D002863:Chromogenic Compounds; D004791:Enzyme Inhibitors; D005960:Glucosides; D011994:Recombinant Proteins; C034170:4-nitrophenyl beta-cellobioside; D014995:Xylosidases; D001617:beta-Glucosidase; C026579:exo-1,4-beta-D-xylosidase