Purification and characterization of Thermobifida fusca xylanase 10B.
Thermobifida fusca grows well on cellulose and xylan, and produces a number of cellulases and xylanases. The gene encoding a previously unstudied endoxylanase, xyl10B, was overexpressed in E. coli, and the protein was purified and characterized. Mature Xyl10B is a 43-kDa glycohydrolase with a short basic domain at the C-terminus. It has moderate thermostability, maintaining 50% of its activity after incubation for 16 h at 62 degrees C, and is most active between pH 5 and 8. Xyl10B is produced by growth of T. fusca on xylan or Solka Floc but not on pure cellulose. Mass spectroscopic analysis showed that Xyl10B produces xylobiose as the major product from birchwood and oat spelts xylan and that its hydrolysis products differ from those of T. fusca Xyl11A. Xyl10B hydrolyzes various p-nitrophenyl-sugars, including p-nitrophenyl alpha-D-arabinofuranoside, p-nitrophenyl-beta-D-xylobioside, p-nitrophenyl-beta-D-xyloside, and p-nitrophenyl-beta-D-cellobioside. Xyl11A has higher activity on xylan substrates, but Xyl10B produced more reducing sugars from corn fiber than did Xyl11A.
Kim
Jeong H
JH
Division of Applied Life Science, Graduate School, and Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 660-701, Korea.
Irwin
Diana
D
Wilson
David B
DB
D000192:Actinomycetales / Q000201:enzymology*; D002482:Cellulose / Q000378:metabolism; D003001:Cloning, Molecular; D004187:Disaccharides / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000302:isolation & purification*; D004790:Enzyme Induction; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D014990:Xylans / Q000378:metabolism
D004187:Disaccharides; D011994:Recombinant Proteins; D014990:Xylans; D002482:Cellulose; D043364:Endo-1,4-beta Xylanases; C004173:xylobiose