Rizzatti A C, Jorge J A, Terenzi H F, Rechia C G, Polizeli M L
Departamento de Bioquímica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brazil.
J Ind Microbiol Biotechnol. 2001 Mar;26(3):156-60. doi: 10.1038/sj.jim.7000107.
A beta-D-xylosidase was purified from cultures of a thermotolerant strain of Aspergillus phoenicis grown on xylan at 45 degrees C. The enzyme was purified to homogeneity by chromatography on DEAE-cellulose and Sephadex G-100. The purified enzyme was a monomer of molecular mass 132 kDa by gel filtration and SDS-PAGE. Treatment with endoglycosidase H resulted in a protein with a molecular mass of 104 kDa. The enzyme was a glycoprotein with 43.5% carbohydrate content and exhibited a pl of 3.7. Optima of temperature and pH were 75 degrees C and 4.0-4.5, respectively. The activity was stable at 60 degrees C and had a Km of 2.36 mM for p-nitrophenyl-beta-D-xylopiranoside. The enzyme did not exhibit xylanase, cellulase, galactosidase or arabinosidase activities. The purified enzyme was active against natural substrates, such as xylobiose and xylotriose.
从嗜热菌株嗜热栖热放线菌在45℃下以木聚糖为培养基培养的产物中纯化出一种β-D-木糖苷酶。通过DEAE-纤维素柱色谱和Sephadex G-100凝胶过滤将该酶纯化至同质。经凝胶过滤和SDS-PAGE分析，纯化后的酶是一种分子量为132 kDa的单体。用内切糖苷酶H处理后得到一种分子量为104 kDa的蛋白质。该酶是一种糖蛋白，碳水化合物含量为43.5%，其等电点为3.7。温度和pH的最适值分别为75℃和4.0 - 4.5。该酶在60℃下活性稳定，对对硝基苯基-β-D-吡喃木糖苷的Km值为2.36 mM。该酶不表现出木聚糖酶、纤维素酶、半乳糖苷酶或阿拉伯糖苷酶活性。纯化后的酶对天然底物如木二糖和木三糖具有活性。
