海枣曲霉木聚糖酶降解寡聚木糖的特性  

The Mode of Action of Xylanase from Aspergillus phoenicis on Xylooligosaccharides

作　　者：江均平[1] 严自正[1] 张树政[1] 

机构地区：[1]中国科学院微生物研究所

出　　处：《生物化学与生物物理学报》1995年第3期287-292,共6页

基　　金：中国科学院资助

摘　　要：利用滤纸层析或ＡｃｒｙｌｅｘＰ－２凝胶过滤从落叶松木聚糖硫酸水解液中分离纯化了木二糖至木五糖。采用硅胶薄层层析分析底物和产物的方法研究了海枣霉木聚糖酶降解寡聚木糖的特点。此酶作用于寡糖的最适ｐＨ为５．０，终产物为Ｘ和Ｘ２。酶作用于Ｘ３、Ｘ４及Ｘ５的相对初速度分别为１、３４和４００，Ｘ２几乎不被酶解，推断该酶的底物结合部位至少具有５个亚位点。在高底物浓度，低酶量，远离最适ｐＨ以及在反应初期都能检测到大于底物聚合度的寡糖，表明此酶具有转糖基作用。Xylooligosaccharides (xylobiose through xylopentose) were purified from the acid hydrolysate of larchwood xylan by paper chromatography or Acrylex P-2 gel filtration. The action pattern of xylanase from Aspergillus phoenicis on xylooligosaccharides were revealed by silica gel thin layer chromatographic analysis. The enzyme had a pH optimum of 5.0 for cleaving oligosaccharides to xylose and xylobiose as the end products. Xylanase had almost no activity on xylobiose, and the relative initial reaction rate towards xylotriose, xylotetrose and xylopentose were 1,34 and 400 respectively, which suggested that the substrate-binding site of the enzyme may contain five subsites at least. Under conditions of high substrate concentration, low enzyme concentration, high pH or at the initial reaction stage, some oligosaccharides larger than the starting substrates were produced by transglycosylation reaction.

关 键 词：木聚糖酶 糖苷酶 寡聚木糖 降解特性 海枣曲霉 

分 类 号：Q939.506[生物学—微生物学]