Kiyohara Masashi, Hama Yoichiro, Yamaguchi Kuniko, Ito Makoto
Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581.
J Biochem. 2006 Sep;140(3):369-73. doi: 10.1093/jb/mvj173. Epub 2006 Aug 5.
Recently we reported the molecular cloning and characterization of a novel beta-1,3-xylanase from the marine bacterium Vibrio sp. AX-4 [Kiyohara et al. (2005) Biochem. J. 388, 949-957]. We report here the structural analysis of oligosaccharides generated from beta-1,3-xylan of a siphonous green alga, Caulerpa racemosa var. laete-virens, by the action of beta-1,3-xylanase. The enzyme degraded the polysaccharide producing oligosaccharides with different R(f)s on TLC (EX2-EX5). Sugar component, linkage, and MALDI-TOF-MS analyses revealed that EX2 and EX3 were Xyl-1,3-Xyl and Xyl-1,3-Xyl-1,3-Xyl, respectively. On the other hand, EX4 was a mixture of Glc-1,3-Xyl-1,3-Xyl, Xyl-1,4-Xyl-1,3-Xyl and Xyl-1,3-Xyl-1,4-Xyl, while EX5 was a mixture of tetra-saccharides containing 3-substitued Glc in addition to the same components of EX4. Branching was not likely present in EXOs prepared from the polysaccharide by the enzyme. These results strongly suggest that the C. racemosa beta-1,3-xylan is a linear heteropolysaccharide containing 1,3-Glc and 1,4-Xyl both of which are thought to be located within a beta-1,3-Xyl chain and linked via covalent bonds. This report indicates the usefulness of the enzyme for the structural analysis of beta-1,3-xylan.
最近，我们报道了从海洋细菌弧菌属AX-4中克隆并鉴定出一种新型β-1,3-木聚糖酶[Kiyohara等人（2005年），《生物化学杂志》388卷，949 - 957页]。在此，我们报告了该β-1,3-木聚糖酶作用于一种管藻目绿藻总状蕨藻变种亮绿蕨藻的β-1,3-木聚糖所产生的寡糖的结构分析。该酶降解多糖产生了在薄层层析（TLC）上具有不同Rf值的寡糖（EX2 - EX5）。糖成分、连接方式以及基质辅助激光解吸电离飞行时间质谱（MALDI - TOF - MS）分析表明，EX2和EX3分别是木糖-1,3-木糖和木糖-1,3-木糖-1,3-木糖。另一方面，EX4是葡萄糖-1,3-木糖-1,3-木糖、木糖-1,4-木糖-1,3-木糖和木糖-1,3-木糖-1,4-木糖的混合物，而EX5除了含有EX4的相同成分外，还是含有3-取代葡萄糖的四糖混合物。该酶从多糖制备的外切寡糖中不太可能存在分支。这些结果有力地表明，总状蕨藻的β-1,3-木聚糖是一种线性杂多糖，含有1,3-葡萄糖和1,4-木糖，二者均被认为位于β-1,3-木糖链内并通过共价键相连。本报告表明了该酶在β-1,3-木聚糖结构分析中的实用性。
