title: Purification and characterization of an endoxylanase from Trichoderma koningii G-39.
abstract: Trichoderma koningii G-39 produced xylanases in submerged culture using oat spelt xylan or crystalline cellulose, Avicel, as the sole carbon source. A low-Mr xylanase was purified from the culture filtrate by ion-exchange chromatography on SP-Trisacryl-M and gel filtration on Fractogel TSK HW-50F. It was homogeneous on SDS/PAGE and isoelectric focusing. A typical procedure provided about 11-fold purification with 4.5% protein yield and 50% activity recovery. The purified enzyme has an Mr value of about 21,500 and a pI of 8.9. Its specific activity was 6100 units/mg of protein, with optimal activity towards 0.5% xylan at about pH 5.5 and 60 degrees C. The purified enzyme had no activity against CM-cellulose with a degree of substitution of 0.63. It also showed no beta-xylosidase activity. The Km and Vmax. values, as determined with the soluble fraction of oat spelt xylan as substrate, were 0.70 mg/ml and 1.85 x 10(6) mumol/min per mg of enzyme respectively. Hg2+ (1 mM) and SDS (10 mM) completely inhibited xylanase activity, whereas Ca2+ showed no significant effect on the enzyme activity at 1 mM, but gave 80% inhibition at 10 mM. The enzyme contained about 4.4% carbohydrate and showed an immunological relationship to a cellobiohydrolase from the same fungal strain.
authors.affiliation: Institute of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: L
authors.initials: L
authors.lastname: Huang
authors.forename: T H
authors.initials: TH
authors.lastname: Hseu
authors.forename: T T
authors.initials: TT
authors.lastname: Wey
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001345:Autoradiography; D015153:Blotting, Western; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases; D006026:Glycoside Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D005779:Immunodiffusion; D007525:Isoelectric Focusing; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D000596:Amino Acids; D006026:Glycoside Hydrolases; D043364:Endo-1,4-beta Xylanases