Division of Biotechnology, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan, Jeonbuk 570-752, Republic of Korea.
J Biosci Bioeng. 2013 Aug;116(2):152-9. doi: 10.1016/j.jbiosc.2013.02.004. Epub 2013 Mar 7.
A bifunctional xylosidase/arabinofuranosidase gene (PcXyl) was cloned from the cDNA library of Phanerochaete chrysosporium and further expressed in Pichia pastoris. Enzymatic assay indicated that P. pastoris produced rPcXyl at a level of 26,141 U l⁻¹. The xylosidase and arabinofuranosidase activities of rPcXyl were maximized, respectively, at pHs of 5.0 and 5.5 and temperatures of 45°C and 50°C. SDS-PAGE revealed a single band of purified rPcXyl of 83 kDa. Cu²⁺ and Zn²⁺ completely inhibited the enzyme activity of rPcXyl. The enzyme activity of rPcXyl was increased 151%, 126% and 123%, respectively, in the presence of glucose, xylose and arabinose at concentrations of 5 mM. rPcXyl hydrolyzed xylobiose to xylose and xylotriose to xylose and xylobiose, indicating rPcXyl acts as an exo-type enzyme. Additionally, rPcXyl enhanced xylose release from xylan substrates in synergy with rPcXynC.
从黄孢原毛平革菌 cDNA 文库中克隆了一种具有木聚糖酶/阿拉伯呋喃糖苷酶活性的双功能基因（PcXyl），并在毕赤酵母中进一步表达。酶活性测定表明，毕赤酵母表达的 rPcXyl 酶活达到 26141 U/L。rPcXyl 的木聚糖酶和阿拉伯呋喃糖苷酶的最适 pH 分别为 5.0 和 5.5，最适温度分别为 45°C 和 50°C。SDS-PAGE 显示纯化的 rPcXyl 为 83 kDa 的单一条带。Cu²⁺和 Zn²⁺完全抑制 rPcXyl 的酶活性。在 5mM 浓度下，葡萄糖、木糖和阿拉伯糖分别使 rPcXyl 的酶活性提高了 151%、126%和 123%。rPcXyl 将木二糖水解为木糖和木三糖，将木二糖水解为木糖和木二糖，表明 rPcXyl 是一种外切酶。此外，rPcXyl 与 rPcXynC 协同作用，增强了木聚糖底物中木糖的释放。
