title: An alkali-stable enzyme with laccase activity from entophytic fungus and the enzymatic modification of alkali lignin.
abstract: Mycelia Sterilia YY-5, an entophytic fungus, was isolated from Rhus chinensis Mill and its extracellular enzyme had a higher laccase activity (MS-Lac). After been purified by anion exchange and gel filtration chromatography, MS-Lac, which had a molecular mass of 45 kDa, was found to be an alkali-stable enzyme with an optimum pH of 10.0 and capable of retaining 80% activity after incubation for 72 h with syringaldazine as substrate. It was also found that syringaldazine had a higher affinity than 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulphonate (ABTS) as substrate for MS-Lac, which was determined in sodium phosphate buffer (pH 6.0, 0.1M) at 30 degrees C. Meanwhile, the lignin modification, catalyzed by MS-Lac, indicated that it could oxidize the phenolic hydroxyl, side chain substituent or carbonyl group of spruce alkali lignin in cetyltrimethylammonium bromide (CTAB) reversed micelles (20 mM, pH 6.0, W/O=40) and steam-exploded wheat straw alkali lignin in NaOH solution (20 mM, pH 10.0).
authors: State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, PR China.
authors: Qiu
authors: Q
authors: Weihua
authors: Chen
authors: C
authors: Hongzhang
mesh_terms: D002850:Chromatography, Gel; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism; D006835:Hydrazones / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000302:isolation & purification / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D008970:Molecular Weight; D025282:Mycelium / Q000201:enzymology; D010084:Oxidation-Reduction; D029045:Rhus / Q000201:enzymology*; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D005656:Fungal Proteins; D006835:Hydrazones; C009370:syringaldazine; D008031:Lignin; D042845:Laccase