Topic
Xylanase
About: Xylanase is a research topic. Over the lifetime, 7099 publications have been published within this topic receiving 163793 citations.
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TL;DR: This is the first report on hemi-cellulose degrading halo-alkali-thermotolerant enzyme from a moderately halophilic Gram-positive Gracilibacillus species.
62 citations
TL;DR: A proline residue in the middle of the alpha-helix alpha6 which may be contributing to better packing is observed for the first time in the F/10 family xylanases, and the refined protein model has allowed a detailed comparison with the other known structures in the P21 family of enzymes.
62 citations
TL;DR: Melanocarpus albomyces IIS-68, a thermophilic fungus was used for the production of extracellular xylanase on various agroresidues in solid-state fermentation (SSF), and studies with electron micrographs indicated that culture filtrate proteins were able to degrade wall polymers.
62 citations
TL;DR: Determination of kcat/Km revealed that the enzyme hydrolysed oat spelts and birchwood xylans, 15-30 times more efficiently than CMC, and attacked preferentially the internal glycosidic bonds of xylo- and 4-methylumbelliferyl cello-oligosaccharides [MeUmb(Glc)n].
62 citations
TL;DR: The structure of IXT6 was compared with the highly homologous extracellular xylanase XT6, revealing a number of structural differences between the active sites of the two enzymes, which may account for the significant differences in the substrate specificities of these otherwise very similar enzymes.
Abstract: Geobacillus stearothermophilus T-6 is a thermophilic Gram-positive bacterium that produces two selective family 10 xylanases which both take part in the complete degradation and utilization of the xylan polymer. The two xylanases exhibit significantly different substrate specificities. While the extracellular xylanase (XT6; MW 43.8 kDa) hydrolyzes the long and branched native xylan polymer, the intracellular xylanase (IXT6; MW 38.6 kDa) preferentially hydrolyzes only short xylo-oligosaccharides. In this study, the detailed three-dimensional structure of IXT6 is reported, as determined by X-ray crystallography. It was initially solved by molecular replacement and then refined at 1.45 A resolution to a final R factor of 15.0% and an R(free) of 19.0%. As expected, the structure forms the classical (alpha/beta)(8) fold, in which the two catalytic residues (Glu134 and Glu241) are located on the inner surface of the central cavity. The structure of IXT6 was compared with the highly homologous extracellular xylanase XT6, revealing a number of structural differences between the active sites of the two enzymes. In particular, structural differences derived from the unique subdomain in the carboxy-terminal region of XT6, which is completely absent in IXT6. These structural modifications may account for the significant differences in the substrate specificities of these otherwise very similar enzymes.
62 citations