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重组大肠杆菌产生的解淀粉欧文氏菌β-木糖苷酶/α-阿拉伯呋喃糖苷酶的特性。

Characterization of a Paenibacillus woosongensis beta-Xylosidase/alpha-Arabinofuranosidase produced by recombinant Escherichia coli.

机构信息

Department of Food Science and Biotechnology, Woosong University, Daejeon 300-718, Korea.

出版信息

J Microbiol Biotechnol. 2010 Dec;20(12):1711-6.

Abstract

A gene encoding the beta-xylosidase/alpha-arabinofuranosidase (XylC) of Paenibacillus woosongensis was cloned into Escherichia coli. This xylC gene consisted of 1,425 nucleotides, encoding a polypeptide of 474 amino acid residues. The deduced amino acid sequence exhibited an 80% similarity with those of both Clostridium stercorarium beta-xylosidase/alpha-N-arabinosidase and Bacillus cellulosilyticus alpha-arabinofuranosidase, belonging to the glycosyl hydrolase family 43. The structural gene was subcloned with a Cterminal His-tag into a pET23a(+) expression vector. The His-tagged XylC, purified from a cell-free extract of a recombinant E. coli BL21(DE3) Codon Plus carrying a xylC gene by affinity chromatography, was active on paranitrophenyl- alpha-arabinofuranoside (pNPA) as well as paranitrophenyl- beta-xylopyranoside (pNPX). However, the enzymatic activities for the substrates were somewhat incongruously influenced by reaction pHs and temperatures. The enzyme was also affected by various chemicals at different levels. SDS (5 mM) inhibited the enzymatic activity for pNPX, while enhancing the enzymatic activity for pNPA. Enzyme activity was also found to be inhibited by addition of pentose or hexose. The Michaelis constant and maximum velocity of the purified enzyme were determined for hydrolysis of pNPX and pNPA, respectively.

摘要

一种来自解淀粉芽孢杆菌(Paenibacillus woosongensis)的编码β-木糖苷酶/α-L-阿拉伯呋喃糖苷酶(XylC)的基因被克隆到大肠杆菌中。该 xylC 基因由 1425 个核苷酸组成,编码 474 个氨基酸残基的多肽。推导的氨基酸序列与梭状芽胞杆菌β-木糖苷酶/α-N-阿拉伯糖苷酶和纤维二糖裂合酶的氨基酸序列具有 80%的相似性,属于糖苷水解酶家族 43。结构基因在 C 端带有 His 标签被亚克隆到 pET23a(+)表达载体中。His 标记的 XylC 从携带 xylC 基因的重组大肠杆菌 BL21(DE3) Codon Plus 的无细胞提取物中通过亲和层析纯化,对对硝基苯-α-L-阿拉伯呋喃糖苷(pNPA)和对硝基苯-β-木糖苷(pNPX)均具有活性。然而,酶的底物的活性在不同的 pH 值和温度下受到影响。该酶也受到不同水平的各种化学物质的影响。SDS(5 mM)抑制 pNPX 的酶活性,同时增强 pNPA 的酶活性。还发现酶活性受到戊糖或己糖的添加抑制。分别测定了纯化酶对 pNPX 和 pNPA 水解的米氏常数和最大速度。

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