01733nas a2200229   4500008004100000022001400041245015100055210006900206260007900275300001000354490000700364520082100371653002501192653002201217653002601239653003201265100002101297700002201318700002001340700001901360856012401379       2006                        eng d  a0141-022900aStructural and active site modification studies implicate Glu, Trp and Arg in the activity of xylanase from alkalophilic Bacillus sp (NCL 87-6-10)0 aStructural and active site modification studies implicate Glu Tr  a360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USAbELSEVIER SCIENCE INCcJUN  a67-730 v393 a<p>Structural studies and residue modification using group specific reagents were used to ascertain the role of different functional groups in xylanase from alkalophilic Bacillus sp. (NCL 87-6-10). Treatment with N-bromosuccinimide resulted in fast enzyme inactivation. Reaction with Woodward's reagent K resulted in initial fast followed by slower inactivation. In both cases enzyme was protected against inactivation by the substrate, xylan. The reaction of the enzyme with phenylglyoxal has revealed one essential arginine residue at the active site. The three-dimensional structural analysis of the xylanase at 2.8 angstrom resolution also implicates involvement of Trp, and Arg residues and carboxylate groups in the binding of substrate and in the catalysis of xylanase. (c) 2005 Published by Elsevier Inc.</p>10aactive-site residues10aalkaline xylanase10aChemical modification10athree-dimensional structure1 aBalakrishnan, H.1 aSatyanarayana, L.1 aGaikwad, S., M.1 aSuresh, C., G.  uhttps://library.ncl.res.in/content/structural-and-active-site-modification-studies-implicate-glu-trp-and-arg-activity-002087nas a2200229   4500008004100000022001400041245011300055210006900168260011100237300001200348490000700360520113600367653002501503653005401528653002501582653003201607100002201639700002501661700002001686700001901706856013201725       2013                        eng d  a0929-866500aCrystal structure and fluorescence analysis of alkaline thermostable xylanase from bacillus sp (NCL 87-6-10)0 aCrystal structure and fluorescence analysis of alkaline thermost  aEXECUTIVE STE Y-2, PO BOX 7917, SAIF ZONE, 1200 BR SHARJAH, U ARAB EMIRATESbBENTHAM SCIENCE PUBL LTDcFEB  a125-1320 v203 a<p>Structural information deduced from the new crystal form of xylanase from Bacillus sp (NCL 87-6-10) (ATBXYL-C) helped us to identify the active site and interpret the stability of the enzyme. The analysis of the tetragonal crystal structure of ATBXYL-C with a bound and cleaved xylotriose revealed the two glutamic acid residues in the structure that could act as nucleophile (Glu94) and base (Glu184) in the enzyme activity and also the tryptophan residues interacting with the substrate. The cleavage of xylotriose in the crystal showed xylobiose to be the major product. Intrinsic fluorescence of the enzyme showed the presence of tryptophans in partially exposed to the solvent at the active site and surface tryptophans in electropositive environment. The titration experiments with xylobiose and xylotriose revealed slightly enhanced preference for longer chain X3 compared with X2. The crystal structure also account for some of the factors, such as increased number of ionic interactions and additional interactions at the N-terminus, which contributed to increased alkalophilicity and thermostability of the enzyme.</p>10aactive site residues10aAlkaline thermophile Bacillus xylanase (ATBXYL-C)10afluorescence studies10athree-dimensional structure1 aSatyanarayana, L.1 aGaikwad, Sushama, M.1 aBalkrishnan, H.1 aSuresh, C., G.  uhttps://library.ncl.res.in/content/crystal-structure-and-fluorescence-analysis-alkaline-thermostable-xylanase-bacillus-sp-ncl-0