从专性厌氧菌白色瘤胃球菌中克隆和测序纤维二糖2-表异构酶基因。
Cloning and sequencing of the cellobiose 2-epimerase gene from an obligatory anaerobe, Ruminococcus albus.
作者信息
Ito Shigeaki, Hamada Shigeki, Yamaguchi Kozo, Umene Shingo, Ito Hiroyuki, Matsui Hirokazu, Ozawa Tadahiro, Taguchi Hidenori, Watanabe Jun, Wasaki Jun, Ito Susumu
机构信息
Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo 060-8589, Japan.
出版信息
Biochem Biophys Res Commun. 2007 Aug 31;360(3):640-5. doi: 10.1016/j.bbrc.2007.06.091. Epub 2007 Jun 26.
Cellobiose 2-epimerase (EC 5.1.3.11) was first identified in 1967 as an extracellular enzyme that catalyzes the reversible epimerization between cellobiose and 4-O-beta-D-glucopyranosyl-D-mannose in a culture broth of Ruminococcus albus 7 (ATCC 27210(T)). Here, for the first time, we describe the purification of cellobiose 2-epimerase from R. albus NE1. The enzyme was found to 2-epimerize the reducing terminal glucose moieties of cellotriose and cellotetraose in addition to cellobiose. The gene encoding cellobiose 2-epimerase comprises 1170 bp (389 amino acids) and is present as a single copy in the genome. The deduced amino acid sequence of the mature enzyme contains the possible catalytic residues Arg52, His243, Glu246, and His374. Sequence analysis shows the gene shares a very low level of homology with N-acetyl-D-glucosamine 2-epimerases (EC 5.1.3.8), but no significant homology to any other epimerases reported to date.
纤维二糖2-表异构酶（EC 5.1.3.11）于1967年首次被鉴定为一种胞外酶，它能催化在白色瘤胃球菌7（ATCC 27210(T)）培养液中纤维二糖和4-O-β-D-吡喃葡萄糖基-D-甘露糖之间的可逆表异构化反应。在此，我们首次描述了从白色瘤胃球菌NE1中纯化纤维二糖2-表异构酶的过程。除纤维二糖外，该酶还能使纤维三糖和纤维四糖的还原端葡萄糖部分发生2-表异构化反应。编码纤维二糖2-表异构酶的基因由1170个碱基对组成（389个氨基酸），且在基因组中以单拷贝形式存在。成熟酶推导的氨基酸序列包含可能的催化残基Arg52、His243、Glu246和His374。序列分析表明，该基因与N-乙酰-D-葡糖胺2-表异构酶（EC 5.1.3.8）的同源性非常低，但与迄今报道的任何其他表异构酶均无显著同源性。
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