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首页> 外文期刊>Biochimica et biophysica acta: BBA: International journal of biochemistry, biophysics and molecular biololgy. Proteins and Proteomics >A novel domain arrangement in a monomeric cyclodextrin-hydrolyzing enzyme from the hyperthermophile Pyrococcus furiosus
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A novel domain arrangement in a monomeric cyclodextrin-hydrolyzing enzyme from the hyperthermophile Pyrococcus furiosus

机译：嗜热嗜热球菌的单体环糊精水解酶中的新型结构域排列

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摘要

PFTA (Pyrococcus furiosus thermostable amylase) is a hyperthermophilic amylase isolated from the archaeon Pyrococcus furiosus. This enzyme possesses characteristics of both ??-amylase- and cyclodextrin (CD)-hydrolyzing enzymes, allowing it to degrade pullulan, CD and acarbose - activities that are absent in most ??-amylases - without the transferring activity that is common in CD-hydrolyzing enzymes. The crystal structure of PFTA revealed a unique monomeric subunit with an extended N-terminal region and an N??-domain folded into its own active site - a significantly altered domain configuration relative to that of the conventional dimeric CD-hydrolyzing amylases in glycoside hydrolase family 13. The active site is formed by the interface of the N'-domain and the catalytic domain and exhibits a broad and wide-open geometry without the concave pocket that is commonly found in the active sites of maltogenic amylases. The mutation of a residue (Gly415 to Glu) located at the domain interface between the N'- and catalytic domains yielded an enzyme that produced a significantly higher purity maltoheptaose (G7) from ??-CD, supporting the involvement of this interface in substrate recognition and indicating that this mutant enzyme is a suitable candidate for the production of pure G7. The unique configuration of the active site distinguishes this archaic monomeric enzyme from classical bacterial CD-hydrolyzing amylases and provides a molecular basis for its enzymatic characteristics and for its potential use in industrial applications. ? 2012 Elsevier B.V. All rights reserved.
机译：PFTA（激烈热球菌热稳定淀粉酶）是从古细菌激烈热球菌中分离出来的一种超嗜热性淀粉酶。该酶具有β-淀粉酶和环糊精（CD）水解酶的特性，可以降解支链淀粉，CD和阿卡波糖（大多数β-淀粉酶不具备的活性），而没有CD中常见的转移活性。 -水解酶。 PFTA的晶体结构揭示了一个独特的单体亚基，它具有一个延伸的N端区域和一个折叠成其自身活性位点的Nβ结构域-与糖苷水解酶中常规的二聚CD水解淀粉酶相比，其结构域发生了明显变化。家族13。活性位点由N'-结构域和催化结构域的界面形成，并呈现出宽阔的几何形状，而没有通常在麦芽糖化淀粉酶活性位点中发现的凹穴。位于N'-和催化结构域之间的结构域界面处的残基（从Gly415变为Glu）的突变产生了一种酶，该酶从ε-CD产生了明显更高纯度的麦芽七糖（G7），支持了该界面参与底物识别并表明该突变酶是生产纯G7的合适候选物。活性位点的独特构型将这种古老单体酶与经典细菌CD水解淀粉酶区分开来，并为其酶学特性及其在工业应用中的潜在用途提供了分子基础。 ？ 2012 Elsevier B.V.保留所有权利。

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