title: Increased alkali stability in Trichoderma reesei endo-1, 4-beta-xylanase II by site directed mutagenesis.
abstract: A number of engineered Trichoderma reesei endo-beta-1,4-xylanase (Xyn II) mutants were created and activity tests were performed for increased stability. The stability of the earlier characterized mutant Y5 (T2C, T28C, K58R, +191D) was further increased by the mutations creating the constructs P9 (N97R+F93W+H144K), P12 (H144C+N92C), P15 (F180Q+H144C+N92C) and P21 (H22K+F180Q+H144C+N92C). The resistance towards thermal inactivation at alkaline pH was increased in all of the mutants. Residual activity T(50%) was increased 4-5 degrees C for P9 at pH 9. The performance of the P9 mutant in sulphate pulp bleaching was also tested and was shown to increase brightness markedly compared to the reference. The bleaching results showed the industrial potential of the obtained mutant.
authors.affiliation: Carbozyme Ltd., Keilaranta 16, 02150 Espoo, Finland. Fred.Fenel@carbozyme.fi
authors.forename: Fred
authors.initials: F
authors.lastname: Fenel
authors.forename: Antti-Jussi
authors.initials: AJ
authors.lastname: Zitting
authors.forename: Anne
authors.initials: A
authors.lastname: Kantelinen
mesh_terms: D000468:Alkalies / Q000737:chemistry; D019943:Amino Acid Substitution; D003080:Cold Temperature; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics*; D004795:Enzyme Stability / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D014242:Trichoderma / Q000201:enzymology* / Q000235:genetics
chemical_list: D000468:Alkalies; D005656:Fungal Proteins; D043364:Endo-1,4-beta Xylanases