title: Applicability of recombinant β-xylosidase from the extremely thermophilic bacterium Geobacillus thermodenitrificans in synthesizing alkylxylosides.
abstract: The β-xylosidase encoding gene (XsidB) of the extremely thermophilic bacterium Geobacillus thermodenitrificans has been cloned and expressed in Escherichia coli. The homotrimeric recombinant XsidB is of 204.0kDa, which is optimally active at 60°C and pH 7.0 with T1/2 of 58min at 70°C. The β-xylosidase remains unaffected in the presence of most metal ions and organic solvents. The Km [p-nitrophenyl β-xyloside (pNPX)], Vmax and kcat values of the enzyme are 2×10(-3)M, 1250μmolesmg(-1)min(-1) and 13.20×10(5)min(-1), respectively. The enzyme catalyzes transxylosylation reactions in the presence of alcohols as acceptors. The pharmaceutically important β-methyl-d-xylosides could be produced using pNPX as the donor and methanol as acceptor. The products of transxylosylation were identified by TLC and HPLC, and the structure was confirmed by (1)H NMR analysis. The enzyme is also useful in synthesizing transxylosylation products from the wheat bran hydrolysate.
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. Electronic address: ira_jain1990@yahoo.co.in.
authors.forename: Ira
authors.initials: I
authors.lastname: Jain
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. Electronic address: vikash.udsc@gmail.com.
authors.forename: Vikash
authors.initials: V
authors.lastname: Kumar
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. Electronic address: tsnarayana@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Satyanarayana
mesh_terms: D001483:Base Sequence; D019149:Bioreactors; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli; D056506:Geobacillus / Q000201:enzymology* / Q000235:genetics; D006027:Glycosides / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013696:Temperature; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D006027:Glycosides; D012336:RNA, Ribosomal, 16S; D011994:Recombinant Proteins; C010807:xylosides; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase
keywords: Alkylxylosides; Geobacillus thermodenitrificans; Methylxyloside; Transxylosylation; β-Xylosidase