Cloning and sequencing of the cellobiose 2-epimerase gene from an obligatory anaerobe, Ruminococcus albus
Cloning and sequencing of the cellobiose 2-epimerase gene from an obligatory anaerobe, Ruminococcus albus
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DOI：
10.1016/j.bbrc.2007.06.091
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发表时间：
2007-08-31
影响因子：
3.1
通讯作者：
Ito, Susumu
中科院分区：
文献类型：
--
作者：
Ito, Shigeaki;Hamada, Shigeki;Ito, Susumu
纤维二糖2-外聚酶（Cellobiose 2- epimase, EC 5.1.3.11）是1967年首次发现的一种细胞外酶，在白色瘤胃球菌7 （Ruminococcus albus 7, ATCC 27210(T)）培养液中催化纤维二糖与4- o - β - d -葡萄糖吡喃糖基- d -甘露糖的可逆外聚反应。本文首次报道了从白藜芦醇NE1中纯化纤维素二糖2-外链酶的过程。除纤维素二糖外，该酶还能对纤维素三糖和纤维素四糖的还原端葡萄糖部分进行2-外异构化。编码纤维二糖2- epimase的基因全长1170 bp（389个氨基酸），以单拷贝形式存在于基因组中。推导出成熟酶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 -葡萄糖胺2-外膜酶（EC 5.1.3.8）具有极低的同源性，但与迄今报道的其他外膜酶无显著的同源性。(c) 2007爱思唯尔公司版权所有。
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. (c) 2007 Elsevier Inc. All rights reserved.