Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 N. University St, Peoria, IL 61604, USA.
Biotechnol Lett. 2011 Oct;33(10):2013-8. doi: 10.1007/s10529-011-0658-9. Epub 2011 Jun 14.
Acremonium zeae, one of the most prevalent fungal colonists of preharvest corn, possesses a suite of hemicellulolytic activities including xylanase, xylosidase, and arabinofuranosidase. Two enzymes with arabinofuranosidase activity were purified from cell-free culture supernatants of A. zeae grown on oat spelt xylan. A 47 kDa enzyme (AF47) was optimally active at 37 °C and pH 6.0, and had a specific activity for 4-nitrophenyl-α-L-arabinofuranoside (4NPA) of 6.2 U/mg. A 30 kDa enzyme (AF30) was optimally active at 50 °C and pH 4.5, and had a specific activity for 4NPA of 12.4 U/mg. AF47 hydrolyzed 4-nitrophenyl-β-D-xylopyranoside, 4-nitrophenyl-β-D-glucopyranoside, and 4-nitrophenyl-β-D-cellobioside, as well as producing reducing sugars from corn fiber, wheat, and oat spelt arabinoxylan. AF30 had little detectable activity on the 4-nitrophenyl substrates, except for 4NPA, but activity on arabinoxylans from corn fiber, wheat, and oat spelt was at least 7-fold higher than AF47, with specific activities of 109, 358, and 153 U/mg, respectively. A combination of the two enzymes released 61 and 88% of the total arabinose from corn fiber and wheat arabinoxylans. The arabinofuranosidases produced by A. zeae may have industrial application for the enzymatic hydrolysis of recalcitrant lignocellulosic feedstocks such as corn fiber and wheat straw.
蜡蚧轮枝菌是一种常见的玉米收获前真菌定居者，具有一系列半纤维素水解酶活性，包括木聚糖酶、木糖苷酶和阿拉伯呋喃糖苷酶。从在燕麦黑麦木聚糖上生长的蜡蚧轮枝菌无细胞培养上清液中纯化了两种具有阿拉伯呋喃糖苷酶活性的酶。一种 47 kDa 的酶（AF47）在 37°C 和 pH6.0 时活性最佳，对 4-硝基苯-α-L-阿拉伯呋喃糖苷（4NPA）的比活为 6.2 U/mg。一种 30 kDa 的酶（AF30）在 50°C 和 pH4.5 时活性最佳，对 4NPA 的比活为 12.4 U/mg。AF47 水解 4-硝基苯-β-D-木吡喃糖苷、4-硝基苯-β-D-葡萄糖苷和 4-硝基苯-β-D-纤维二糖苷，并从玉米纤维、小麦和燕麦黑麦阿拉伯木聚糖产生还原糖。AF30 对 4-硝基苯底物几乎没有检测到活性，除了 4NPA 外，但对玉米纤维、小麦和燕麦黑麦阿拉伯木聚糖的活性至少比 AF47 高 7 倍，比活分别为 109、358 和 153 U/mg。两种酶的组合从玉米纤维和小麦阿拉伯木聚糖中释放了 61%和 88%的总阿拉伯糖。蜡蚧轮枝菌产生的阿拉伯呋喃糖苷酶可能在酶解玉米纤维和小麦秸秆等难处理木质纤维素饲料方面具有工业应用。
