635-78-9Relevant academic research and scientific papers
Building three-dimensional nanostructures with active enzymes by surface templated layer-by-layer assembly
Rauf, Sakandar,Zhou, Dejian,Abell, Chris,Klenerman, David,Kang, Dae-Joon
, p. 1721 - 1723 (2006)
We show that well-defined three-dimensional nanostructures of functional enzymes can be controllably fabricated by layer-by-layer assembly of avidin and biotinylated horseradish peroxidase on micro-contact printing patterned surface templates. The Royal S
A Fluorogenic Trehalose Probe for Tracking Phagocytosed Mycobacterium tuberculosis
Bertozzi, Carolyn R.,Dai, Tingting,Jiang, Ke,Kamariza, Mireille,Rao, Jianghong,Xie, Jinghang,Zhu, Qihua
, p. 15259 - 15264 (2020)
Tuberculosis (TB) disease is a global epidemic caused by the pathogenic Mycobacterium tuberculosis (Mtb). Tools that can track the replication status of viable Mtb cells within macrophages are vital for the elucidation of host-pathogen interactions. Here, we present a cephalosphorinase-dependent green trehalose (CDG-Tre) fluorogenic probe that enables fluorescence labeling of single live Bacille Calmette-Guérin (BCG) cells within macrophages at concentrations as low as 2 μM. CDG-Tre fluoresces upon activation by BlaC, the β-lactamase uniquely expressed by Mtb, and the fluorescent product is subsequently incorporated within the bacterial cell wall via trehalose metabolic pathway. CDG-Tre showed high selectivity for mycobacteria over other clinically prevalent species in the Corynebacterineae suborder. The unique labeling strategy of BCG by CDG-Tre provides a versatile tool for tracking Mtb in both pre- and postphagocytosis and elucidating fundamental physiological and pathological processes related to the mycomembrane.
Increased potassium conductance of brain mitochondria induces resistance to permeability transition by enhancing matrix volume
Hansson, Magnus J.,Morota, Saori,Teilum, Maria,Mattiasson, Gustav,Uchino, Hiroyuki,Elmer, Eskil
, p. 741 - 750 (2010)
Modulation of K+ conductance of the inner mitochondrial membrane has been proposed to mediate preconditioning in ischemia-reperfusion injury. The mechanism is not entirely understood, but it has been linked to a decreased activation of mitochondrial permeability transition (mPT). In the present study K+ channel activity was mimicked by picomolar concentrations of valinomycin. Isolated brain mitochondria were exposed to continuous infusions of calcium. Monitoring of extramitochondrial Ca2+ and mitochondrial respiration provided a quantitative assay for mPT sensitivity by determining calcium retention capacity (CRC). Valinomycin and cyclophilin D inhibition separately and additively increased CRC. Comparable degrees of respiratory uncoupling induced by increased K+ or H+ conductance had opposite effects on mPT sensitivity. Protonophores dose-dependently decreased CRC, demonstrating that so-called mild uncoupling was not beneficial per se. The putative mitoKATP channel opener diazoxide did not mimic the effect of valinomycin. An alkaline matrix pH was required for mitochondria to retain calcium, but increased K+ conductance did not result in augmented ΔpH. The beneficial effect of valinomycin on CRC was not mediated by H2O2-induced protein kinase C∈ activation. Rather, increased K+ conductance reduced H2O2 generation during calcium infusion. Lowering the osmolarity of the buffer induced an increase in mitochondrial volume and improved CRC similar to valinomycin without inducing uncoupling or otherwise affecting respiration. We propose that increased potassium conductance in brain mitochondria may cause a direct physiological effect on matrix volume inducing resistance to pathological calcium challenges.
Target-Selective Fluorescence Imaging and Photocytotoxicity against H2O2 High-Expressing Cancer Cells Using a Photoactivatable Theranostic Agent
Takagi, Ryoma,Takeda, Ayano,Takahashi, Daisuke,Toshima, Kazunobu
, p. 2656 - 2659 (2017)
A purpose-designed and synthesized H2O2-reactive and photoactivatable theranostic agent 1 consisting of 1) an arylboronic acid moiety, 2) pro-fluorophore moiety, and 3) photoactivatable moiety (photosensitizer), selectively and effectively reacted with H2O2 while simultaneously releasing resorufin for fluorescence detection under neutral aqueous conditions. In addition, 1 was cell-permeable, and exhibited effective photocytotoxicity against fluorescently visualized cells only upon photoirradiation. The results also showed that 1 produced a selective fluorescence response to H2O2, even in living cultured cells.
Cu2+-Modified Metal–Organic Framework Nanoparticles: A Peroxidase-Mimicking Nanoenzyme
Chen, Wei-Hai,Vázquez-González, Margarita,Kozell, Anna,Cecconello, Alessandro,Willner, Itamar
, (2018)
The synthesis and characterization of UiO-type metal–organic framework nanoparticles (NMOFs) composed of Zr4+ ions bridged by 2,2′-bipyridine-5,5′-dicarboxylic acid ligands and the postmodification of the NMOFs with Cu2+ ions are described. The resulting Cu2+-modified NMOFs, Cu2+-NMOFs, exhibit peroxidase-like catalytic activities reflected by the catalyzed oxidation of Amplex-Red to the fluorescent Resorufin by H2O2, the catalyzed oxidation of dopamine to aminochrome by H2O2, and the catalyzed generation of chemiluminescence in the presence of luminol/H2O2. Also, the Cu2+-NMOFs mimic NADH peroxidase functions and catalyze the oxidation of dihydronicotinamide adenine dinucleotide, NADH, to nicotinamide adenine dinucleotide, NAD+, in the presence of H2O2. The Cu2+-NMOFs-catalyzed generation of chemiluminescence in the presence of luminol/H2O2 is used to develop a glucose sensor by monitoring the H2O2 formed by the aerobic oxidation of glucose to gluconic acid in the presence of glucose oxidase. Furthermore, loading the Cu2+-NMOFs with fluorescein and activating the catalyzed generation of chemiluminescence in the presence of luminol/H2O2 yield an efficient chemiluminescence resonance energy transfer (CRET) process to the fluorescein reflected by the activation of the fluorescence of the dye (λ = 520 nm, CRET efficiency 35%).
Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity
Zhang, Yuwei,Lucas, J. Matthew,Song, Ping,Beberwyck, Brandon,Fu, Qiang,Xu, Weilin,Alivisatos, A. Paul
, p. 8959 - 8964 (2015)
For the practical application of nanocatalysts, it is desirable to understand the spatiotemporal fluctuations of nanocatalytic activity at the single-nanoparticle level. Here we use time-lapsed superresolution mapping of single-molecule catalysis events on individual nanoparticles to observe time-varying changes in the spatial distribution of catalysis events on Sb-doped TiO2 nanorods and Au triangle nanoplates. Compared with the active sites on well-defined surface facets, the defects of the nanoparticle catalysts possess higher intrinsic reactivity but lower stability. Corners and ends are more reactive but also less stable than flat surfaces. Averaged over time, the most stable sites dominate the total apparent activity of single nanocatalysts. However, the active sites with higher intrinsic activity but lower stability show activity at earlier time points before deactivating. Unexpectedly, some active sites are found to recover their activity ("self-healing") after deactivation, which is probably due to desorption of the adsorbate. Our superresolution measurement of different types of active catalytic sites, over both space and time, leads to a more comprehensive understanding of reactivity patterns and may enable the design of new and more productive heterogeneous catalysts.
A 3,7-Dihydroxyphenoxazine-based Fluorescent Probe for Selective Detection of Intracellular Hydrogen Peroxide
Han, Zhiqiang,Liang, Xiao,Ren, Xuejiao,Shang, Luqing,Yin, Zheng
, p. 818 - 822 (2016)
A novel N-borylbenzyloxycarbonyl-3,7-dihydroxyphenoxazine fluorescent probe (NBCD) for detecting H2O2 in living cells is described. The probe could achieve high selectivity for detecting H2O2 over other biological reactive oxygen species (ROS). In addition, upon addition of H2O2, NBCD exhibited color change from colorless to pink, which makes it a "naked-eye" probe for H2O2 detection. NBCD could not only be used to detect enzymatically generated H2O2 but also to detect H2O2 in living systems by using fluorescence spectroscopy, with a detection limit of 2 μm. Importantly, NBCD enabled the visualization of epidermal growth factor (EGF)-stimulated H2O2 generation inside the cells.
Polyphenol-Mediated Assembly of Proteins for Engineering Functional Materials
Caruso, Frank,Guo, Rui,Han, Yiyuan,Lin, Zhixing,Richardson, Joseph J.,Yun, Gyeongwon,Zhou, Jiajing
, p. 15618 - 15625 (2020)
Functional materials composed of proteins have attracted much interest owing to the inherent and diverse functionality of proteins. However, establishing general techniques for assembling proteins into nanomaterials is challenging owing to the complex physicochemical nature and potential denaturation of proteins. Here, a simple, versatile strategy is introduced to fabricate functional protein assemblies through the interfacial assembly of proteins and polyphenols (e.g., tannic acid) on various substrates (organic, inorganic, and biological). The dominant interactions (hydrogen-bonding, hydrophobic, and ionic) between the proteins and tannic acid were elucidated; most proteins undergo multiple noncovalent stabilizing interactions with polyphenols, which can be used to engineer responsiveness into the assemblies. The proteins retain their structure and function within the assemblies, thereby enabling their use in various applications (e.g., catalysis, fluorescence imaging, and cell targeting).
Development of an improved Amplex Red peroxidation activity assay for screening cytochrome P450 variants and identification of a novel mutant of the thermophilic CYP119
Ba?lar, M. Semih,Sakall?, Tu??e,Güralp, Gülce,Kestevur Do?ru, Ekin,Hakl?, Emre,Surmeli, Nur Basak
, p. 949 - 962 (2020)
Abstract: Biocatalysts are increasingly utilized in the synthesis of drugs and agrochemicals as an alternative to chemical catalysis. They are preferred in the synthesis of enantiopure products due to their high regioselectivity and enantioselectivity. Cytochrome P450 (P450) oxygenases are valuable biocatalysts, since they catalyze the oxidation of carbon–hydrogen bonds with high efficiency and selectivity. However, practical use of P450s is limited due to their need for expensive cofactors and electron transport partners. P450s can employ hydrogen peroxide (H2O2) as an oxygen and electron donor, but the reaction with H2O2 is inefficient. The development of P450s that can use H2O2 will expand their applications. Here, an assay that utilizes Amplex Red peroxidation, to rapidly screen H2O2-dependent activity of P450 mutants in cell lysate was developed. This assay was employed to identify mutants of CYP119, a thermophilic P450 from Sulfolobus acidocaldarius, with increased peroxidation activity. A mutant library of CYP119 containing substitutions in the heme active site was constructed via combinatorial active-site saturation test and screened for improved activity. Screening of 158 colonies led to five mutants with higher activity. Among improved variants, T213R/T214I was characterized. T213R/T214I exhibited fivefold higher kcat for Amplex Red peroxidation and twofold higher kcat for styrene epoxidation. T213R/T214I showed higher stability towards heme degradation by H2O2. While the Km for H2O2 and styrene were not altered by the mutation, a fourfold decrease in the affinity for another substrate, lauric acid, was observed. In conclusion, Amplex Red peroxidation screening of CYP119 mutants yielded enzymes with increased peroxide-dependent activity. Graphic abstract: [Figure not available: see fulltext.].
A Reaction-Based Fluorescent Probe for Imaging of Native Hypochlorous Acid
Wang, Jiamin,Men, Yuhui,Niu, Linqiang,Luo, Yang,Zhang, Jian,Zhao, Weili,Wang, Jianhong
, p. 3893 - 3897 (2019)
Hypochlorous acid (HOCl), one of the reactive oxygen species (ROS), is highly reactive and short-lived. It is a challenge to dynamic monitor HOCl activity in living systems. Hence, we synthesized a new fluoresce nt probe RF1 based on protection of the hydroxyl group by N,N-dimethylthiocarbamate recognition group, which reached a low fluorescence background signal and highly sensitive property. On account of the electrophilic addition of Cl+ to the sulfide of thiocarbamate moiety, probe RF1 was converted to resorufin and triggered emitting bright. RF1 showed not only the highly sensitive and selective response to HOCl in vitro, but also can be applied in environmental water samples and detected HOCl by test strips. Besides, the ability of RF1 monitoring HOCl in HeLa cells by exogenous simulation and tracing native HOCl in macrophages cells were also explored.
