海枣曲霉木聚糖酶降解寡聚木糖的特性

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子木二糖至木五糖。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

The Mode of Action of Xylanase from Aspergillus phoenicis on Xylooligosaccharides

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.