Department of Plant Sciences, North Dakota State University, Fargo, North Dakota 58108-6050, United States.
J Agric Food Chem. 2012 Mar 14;60(10):2538-45. doi: 10.1021/jf203407p. Epub 2012 Feb 29.
This paper reports the first isolation from cultures of two endoxylanases secreted by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schweinitz) Petch]. When F. graminearum is grown on wheat bran hydrated with a modified synthetic medium, high xylanase activity can be extracted. The two endoxylanases were identified by LC-MS/MS as the products of genes FGSG_6445 (Genbank gene id 2788192 ) (xylanase 1) and FGSG_3624 (GenBank accession no. AJ863566 ) (xylanase 2) with 61 and 51% sequence coverage, respectively. Both enzymes showed a pH optimum at pH 6, with xylanase 1 exhibiting a wider active pH range (5.5-9) than xlylanase 2 (5.5-7.5). Their temperature dependences were similar, >60% between 35 and 60 °C, with optimal temperatures of 45 °C for xylanase 1 and 50 °C for xylanase 2. Kinetic studies found that both enzymes had a lower K(m) for linear beachwood xylan than arabinoxylan. For xylanase 2, the V(max) increased with arabinoxylan, but decreased for xylanase 1.
本文报道了从禾谷镰刀菌（Gibberella zeae（Schweinitz）Petch）[有性型为玉蜀黍赤霉（Fusarium graminearum Schwabe）]培养物中分离出的两种内切木聚糖酶。当禾谷镰刀菌在含有改良合成培养基的水合麦麸上生长时，可以提取到高木聚糖酶活性。通过 LC-MS/MS 鉴定，这两种内切木聚糖酶分别是 FGSG_6445（Genbank 基因 ID 2788192）（木聚糖酶 1）和 FGSG_3624（GenBank 登录号 AJ863566）（木聚糖酶 2）基因的产物，分别具有 61%和 51%的序列覆盖率。两种酶的 pH 最适值均为 6，木聚糖酶 1 的活性 pH 范围（5.5-9）比木聚糖酶 2（5.5-7.5）更宽。它们的温度依赖性相似，在 35-60°C 之间超过 60%，木聚糖酶 1 的最适温度为 45°C，木聚糖酶 2 的最适温度为 50°C。动力学研究发现，两种酶对线性柏木聚糖的 K(m)均低于阿拉伯木聚糖。对于木聚糖酶 2，V(max)随阿拉伯木聚糖的增加而增加，但木聚糖酶 1 的 V(max)却下降。
