Department of Biochemistry and Nutrition, Council of Scientific and Industrial Research-Central Food Technological Research Institute (CSIR-CFTRI), Mysore 570020, Karnataka, India.
Carbohydr Polym. 2013 Feb 15;92(2):1978-83. doi: 10.1016/j.carbpol.2012.11.081. Epub 2012 Dec 3.
In the recent years there has been a growing interest in the use of oligosaccharides as prebiotics to modulate gut microbiota with an aim to improve the gut health. Though xylo-oligosaccharides (XOS) have been increasingly used as prebiotics, information pertaining to the enzymes used by lactobacilli to degrade these substrates is scanty. Present investigation reports the purification and characterization of β-D-xylosidase from Lactobacillus brevis NCDC01 grown on XOS. Three sequential steps consisting of ultra-filtration, DEAE cellulose ion-exchange and Sephacryl S-100 gel filtration chromatographies were employed to purify the enzyme to apparent homogeneity and it was found to be monomeric on SDS-PAGE with an apparent molecular mass of ~58.0 kDa. The pH and temperature optima were 6.0 and 40 °C respectively. The enzyme remained stable over a pH range of 5.5-7.5 and up to 50 °C for 30 min. Under optimum pH and temperature with p-nitrophenyl β-D-xylopyranoside as a substrate, the enzyme exhibited a K(m) of 0.87 mM. The enzyme does not require any metal ion for activity or stability but is completely inhibited by Hg(2+), Pb(2+), p-chloromercuribenzoate (PCMB), oxalic acid and citric acid. This is perhaps the first report on the purification and characterization of β-D-xylosidase from Lactobacillus brevis NCDC01.
近年来,人们对使用低聚糖作为益生元来调节肠道微生物群以改善肠道健康的兴趣日益浓厚。尽管木低聚糖 (XOS) 已越来越多地被用作益生元,但有关乳酸菌用于降解这些底物的酶的信息却很少。本研究报告了从以 XOS 为生长基质的短乳杆菌 NCDC01 中纯化和表征β-D-木糖苷酶。采用超滤、DEAE 纤维素离子交换和 Sephacryl S-100 凝胶过滤层析等三个连续步骤对酶进行纯化,达到明显的均一性,SDS-PAGE 显示其为单体,表观分子量约为 58.0 kDa。该酶的最适 pH 和温度分别为 6.0 和 40°C。该酶在 pH 5.5-7.5 范围内稳定,在 50°C 下 30 分钟内保持稳定。在最适 pH 和温度下,以对硝基苯-β-D-木糖苷为底物时,该酶的 K(m)为 0.87 mM。该酶的活性或稳定性不需要任何金属离子,但完全被 Hg(2+)、Pb(2+)、对氯汞苯甲酸 (PCMB)、草酸和柠檬酸抑制。这或许是首次从短乳杆菌 NCDC01 中纯化和表征β-D-木糖苷酶的报道。