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211. Superoxide anion radical generation in the NaOH/H(2)O(2)/Fe(III) system: a spin trapping ESR study

Author

Nie Zhou, Liu Yang-ping, Tian Qiu, and Liu Yang

Subjects
Spin trapping, Superoxide, Inorganic chemistry, Electron Spin Resonance Spectroscopy, Ethylenediaminetetraacetic acid, General Chemistry, Hydrogen-Ion Concentration, Ferric Compounds, chemistry.chemical_compound, chemistry, Superoxides, Nitro, General Materials Science, Chelation, Hydroxyl radical, Hydrogen peroxide, Deoxygenation, Nuclear chemistry
Abstract

Formation of free radical intermediates in a NaOH/H(2)O(2)/Fe(III) system has been studied by ESR spectroscopy in the presence of the spin trap 5,5-dimethy-1-pyrroline N-oxide (DMPO). DMPO/O(2(*) ) (-) and DMPO/(*)OH signals were simultaneously detected in this system, but only the DMPO/(*)OH signal could be observed in the absence of Fe(III). Effects of pH values and Fe(III) concentrations on the ESR signal intensities were investigated in detail. Formation of DMPO/O(2(*) ) (-) adduct was inhibited by the addition of superoxide dismutase (SOD), catalase or nitro blue tetrazolium (NBT), and by chelating the Fe(III) with some chelators, including ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and desferrioxamine (DFO). Deoxygenation from the NaOH/H(2)O(2)/Fe(III) mixture had a slight effect on the formation of DMPO/O(2(*) ) (-). DMPO/O(2(*) ) (-) signal was also detected from the NaOH/H(2)O(2)/Fe(II) mixture, but it can be totally suppressed under anaerobic conditions. Considering the hydrolysis of Fe(III) into polymerization iron species with oxide phases in the alkaline medium, Fe(2)O(3) was directly suspended into a mixture of NaOH/H(2)O(2) for comparison. Fortunately, the presence of Fe(2)O(3) suspension was found to be of benefit to the production of DMPO/O(2(*) ) (-). Influence of aging time of hydrolytic iron species on the superoxide anion radical generation was also studied. These results suggest that the generation of O(2(*) ) (-) from the NaOH/H(2)O(2)/Fe(III) system was probably caused by the heterogeneous surface catalysis initiated by hydrolytic iron species.

Published
2005

228. Eu,Sm,Mn-Doped CaS Nanoparticles with 59.3% Upconversion-Luminescence Quantum Yield: Enabling Ultrasensitive and Facile Smartphone-Based Sulfite Detection

Author

Wang, Jikai, Zhu, Yanli, Grimes, Craig A., Nie, Zhou, and Cai, Qingyun

Abstract

Eu,Sm,Mn-doped CaS (ESM-CaS) nanoparticles demonstrate a remarkable upconversion luminescence (UCL) efficiency with a quantum yield of nearly 60%, enabling many new applications and devices. We describe an ESM-CaS nanoparticle-based paper test strip for one-shot quantitative measurement of sulfite concentration using a smartphone-based reader. The integrated UCL-based sulfite detection system features high sensitivity and facile operation without the need for separation and pretreatment. Moreover, the design principles are general in nature and so can be tailored for the detection and quantification of a variety of other analytes.

Published
2018
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242. Sensitive detection of DNA methyltransferase activity based on supercharged fluorescent protein and template-free DNA polymerization.

Author

Li, Daiqi, Lu, Guoyan, Lei, Chunyang, Wang, Zhen, Li, Lijun, Nie, Zhou, Huang, Yan, and Yao, Shouzhuo

Abstract

DNA methylation, catalyzed by DNA methyltransferases (MTases), is a key component of genetic regulation, and DNA MTases have been regarded as potential targets in anticancer therapy. Herein, based on our previously developed DNA-mediated supercharged green fluorescent protein (ScGFP)/graphene oxide (GO) interaction, coupled with methylation-initiated template- free DNA polymerization, we propose a novel fluorescence assay strategy for sensitive detection of DNA MTase activity. A hairpin DNA with a methylation-sensitive site and an amino-modified 3'-terminal (DNA-1) was designed and worked as a starting molecule. In the presence of DNA MTase, methylation-sensitive restriction endonuclease, and terminal deoxynucleotidyl transferase (TdT), DNA-1 can be sequentially methylated, cleaved, and further elongated. The resulting long DNA fragments quickly bind with ScGFP and form the ScGFP/DNA nanocomplex. Such nanocomplex can effectively protect ScGFP from being adsorbed and quenched by GO. Without the methylation-initiated DNA polymerization, the fluorescence of ScGFP will be quenched by GO. Thus, the DNA MTase activity, which is proportional to the amount of DNA polymerization products, can be measured by reading the fluorescence of ScGFP/GO. The method was successfully used to detect the activity of DNA adenine methylation (Dam) MTase with a wide linear range (0.1-100 U/mL) and a low detection limit of 0.1 U/mL. In addition, the method showed high selectivity and the potential to be applied in a complex sample. Furthermore, this study was successfully extended to evaluate the inhibition effect of 5-fluorouracil on Dam MTase activity and detect TdT activity. [ABSTRACT FROM AUTHOR]

Published
2016
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243. Bioanalytical approaches for the detection of protein acetylation-related enzymes.

Author

Li, Pei, Han, Yitao, Li, Yong, Zhu, Rong, Wang, Huixia, Nie, Zhou, and Yao, Shouzhuo

Subjects
PROTEIN research, ACETYLATION, ACETYLTRANSFERASES, DEACETYLASES, HISTONES
Abstract

Reversible protein acetylation catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDACs) is an essential post-translational modification (PTM) mechanism which correlates largely with epigenetic gene regulation such as transcriptional activation, DNA replication, histone deposition, and DNA repair. Dysfunction of histone acetylation and the aberrant activity of HATs/HDACs is often associated with the pathogenesis of numerous diseases, especially cancer. Therefore, developing potent and specific analytical methods for HATs/HDACs is important for fundamental biochemical research, disease diagnosis and treatment, and drug development. This paper briefly summarizes the general design strategies used in HAT/HDAC sensors, gives a systematic overview of recent advances in the analytical methods for HAT/HDAC enzymatic analysis, classifies these methods by their biorecognition mechanisms and relative applications either in vitro or in living cells, then outlines challenges faced by these bioanalytical methods and offers perspectives on future developments. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Published
2016
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247. Fluorescent RNA Tags for In Situ RNA Imaging in Living Cells.

Author

Yin, Peng, Kuang, Shi, and Nie, Zhou

Abstract

RNA imaging paves the way to investigate RNA function and regulation from the aspect of RNA subcellular localization and expression level. In the past decades, various highly precise and genetic coding fluorescent RNA, which can bind and light up the fluorophore by their specific sequence/structure, has been developed for RNA imaging, including Broccoli, Mango, SRB‐2, RhoBAST, and Pepper et al. In this Review, we summarize the RNA imaging approaches and the progress made in the development of fluorescent RNA. Next, we emphasize the application of fluorescent RNA for in situ RNA imaging in living cells. Of particular note, besides the artificially selected fluorescent RNAs, a new kind of fluorophore that can bind and light up intrinsic RNA structure is described together for the first time. Finally, a summary of current strategies for designing fluorescent RNA and future perspectives are also presented. We hope this expanding topic will inspire the study of the architecture and functions of these fascinating molecular machinery in biological systems. [ABSTRACT FROM AUTHOR]

Published
2023
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