来自嗜热绿菌的一种硫化物：醌氧化还原酶表现出不同寻常的动力学特性。
A sulfide:quinone oxidoreductase from Chlorobaculum tepidum displays unusual kinetic properties.
作者信息
Shuman Kevin E, Hanson Thomas E
机构信息
Department of Biological Sciences, University of Delaware, Newark, DE 19711, USA Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA.
Department of Biological Sciences, University of Delaware, Newark, DE 19711, USA Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA School of Marine Science and Policy, University of Delaware, Newark, DE 19711, USA
出版信息
FEMS Microbiol Lett. 2016 Jun;363(12). doi: 10.1093/femsle/fnw100. Epub 2016 Apr 18.
Sulfide:quinone oxidoreductase (SQR) is the primary sulfide-oxidizing enzyme found in all three domains of life. Of the six phylogenetically distinct types of SQR, four have representatives that have been biochemically characterized. The genome of Chlorobaculum tepidum encodes three SQR homologs. One of these, encoded by CT1087, is a type VI SQR that has been previously shown to be required for growth at high sulfide concentrations and to be expressed in sulfide-dependent manner. Therefore, CT1087 was hypothesized to be a high sulfide adapted SQR. CT1087 was expressed in Escherichia coli with an N-terminal His-tag (CT1087NHis6) and purified by Ni-NTA chromatography. CT1087NHis6 was active and contained FAD as a strongly bound cofactor. The measured kinetic parameters for CT1087NHis6 indicate a low affinity for sulfide and a high enzymatic turnover rate consistent with the hypothesis for its function inferred from genetic and expression data. These are the first kinetic data for a type VI SQR and have implications for structure-function analyses of all SQR's.
硫化物
醌氧化还原酶（SQR）是在生命的所有三个域中发现的主要硫化物氧化酶。在六种系统发育上不同类型的SQR中，有四种具有已进行生化表征的代表。嗜热绿菌（Chlorobaculum tepidum）的基因组编码三种SQR同源物。其中一种由CT1087编码，是VI型SQR，先前已证明它是高硫化物浓度下生长所必需的，并且以硫化物依赖的方式表达。因此，推测CT1087是一种适应高硫化物的SQR。CT1087在带有N端His标签的大肠杆菌（CT1087NHis6）中表达，并通过镍-氮三乙酸（Ni-NTA）色谱法纯化。CT1087NHis6具有活性，并含有作为紧密结合辅因子的黄素腺嘌呤二核苷酸（FAD）。所测得的CT1087NHis6的动力学参数表明其对硫化物的亲和力较低，酶促周转率较高，这与从遗传和表达数据推断出的其功能假设一致。这些是VI型SQR的首批动力学数据，对所有SQR的结构-功能分析具有重要意义。
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