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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
17
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pubmed:dateCreated |
2005-4-25
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pubmed:databankReference |
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pubmed:abstractText |
Reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125 (Rex) hydrolyzes xylooligosaccharides whose degree of polymerization is greater than or equal to 3, releasing the xylose unit at the reducing end. It is a unique exo-type glycoside hydrolase that recognizes the xylose unit at the reducing end in a very strict manner, even discriminating the beta-anomeric hydroxyl configuration from the alpha-anomer or 1-deoxyxylose. We have determined the crystal structures of Rex in unliganded and complex forms at 1.35-2.20-A resolution and revealed the structural aspects of its three subsites ranging from -2 to +1. The structure of Rex was compared with those of endo-type enzymes in glycoside hydrolase subfamily 8a (GH-8a). The catalytic machinery of Rex is basically conserved with other GH-8a enzymes. However, subsite +2 is blocked by a barrier formed by a kink in the loop before helix alpha10. His-319 in this loop forms a direct hydrogen bond with the beta-hydroxyl of xylose at subsite +1, contributing to the specific recognition of anomers at the reducing end.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
29
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pubmed:volume |
280
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
17180-6
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:15718242-Bacillus,
pubmed-meshheading:15718242-Binding Sites,
pubmed-meshheading:15718242-Catalysis,
pubmed-meshheading:15718242-Crystallography, X-Ray,
pubmed-meshheading:15718242-Disaccharides,
pubmed-meshheading:15718242-Electrons,
pubmed-meshheading:15718242-Glycoside Hydrolases,
pubmed-meshheading:15718242-Hydrogen Bonding,
pubmed-meshheading:15718242-Hydrolysis,
pubmed-meshheading:15718242-Kinetics,
pubmed-meshheading:15718242-Ligands,
pubmed-meshheading:15718242-Models, Chemical,
pubmed-meshheading:15718242-Models, Molecular,
pubmed-meshheading:15718242-Mutagenesis, Site-Directed,
pubmed-meshheading:15718242-Oligosaccharides,
pubmed-meshheading:15718242-Protein Binding,
pubmed-meshheading:15718242-Protein Conformation,
pubmed-meshheading:15718242-Protein Structure, Secondary,
pubmed-meshheading:15718242-Substrate Specificity,
pubmed-meshheading:15718242-Time Factors,
pubmed-meshheading:15718242-Xylose,
pubmed-meshheading:15718242-Xylosidases
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pubmed:year |
2005
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pubmed:articleTitle |
Structural basis for the specificity of the reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125.
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pubmed:affiliation |
Department of Biotechnology, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. asfushi@mail.ecc.u-tokyo.ac.jp
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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