Progress toward clonable inorganic nanoparticles.
Progress toward clonable inorganic nanoparticles.
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DOI：
10.1039/c5nr04097c
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发表时间：
2015-11-07
期刊：
影响因子：
6.7
通讯作者：
Ackerson CJ
中科院分区：
文献类型：
--
作者：
Ni TW;Staicu LC;Nemeth RS;Schwartz CL;Crawford D;Seligman JD;Hunter WJ;Pilon-Smits EA;Ackerson CJ
假单胞菌是最近从超积累硒植物Stanleya pinnata的根中分离到的。这种细菌在液体培养中能耐受通常致命浓度的SeO_32−，在液体培养中它还能产生硒纳米颗粒。通过细胞电子断层扫描确定了纳米Se颗粒的结构和细胞超微结构，结果表明纳米Se颗粒在细胞内呈窄分散、对称性不规则，没有可见的膜或结构蛋白壳。对一种具有亚硒酸盐还原能力的分级可溶性胞浆物质的蛋白质质谱分析发现，亚硝酸盐还原酶和谷胱甘肽还原酶同系物是依赖于NADPH的亚硒酸盐还原为零价硒纳米颗粒的候选酶。用商业来源的谷胱甘肽还原酶进行的体外实验表明，该酶可以在NADPH依赖的过程中将SeO_32−(亚硒酸盐)还原为Se纳米颗粒。在纳米颗粒形成过程中，通过蛋白质分析确定酶的消失，这表明谷胱甘肽还原酶与其催化的纳米颗粒的形成有关，或者可能被嵌入其中。化学溶解纳米颗粒会释放出这种酶。纳米颗粒的大小随着SeO_32−浓度的不同而变化，在1.0μM[SeO_32−]下形成的纳米颗粒的尺寸从5 nm到100μM时的最大直径50 nm[SeO_32−]不等。总而言之，我们认为谷胱甘肽还原酶具有可克隆纳米颗粒系统的关键属性：离子还原、纳米颗粒保留和纳米颗粒在酶位置的尺寸控制。
Pseudomonas moraviensis stanleyae was recently isolated from the roots of the Selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32− in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32− (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32− concentration, varying in size form 5nm diameter when formed at 1.0 μM [SeO32−] to 50nm maximum diameter when formed at 100 μM [SeO32−]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.