- Determination of nitrite in waters by microplate fluorescence spectroscopy and HPLC with fluorescence detection
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A selective and versatile fluorescence spectroscopic method for the determination of nitrite in waters has been developed. Nitrite reacts in the presence of mineral acids with the nonfluorescent N-methyl-4-hydrazino-7- nitrobenzofurazan forming N-methyl-4-amino-7-nitrobenzofurazan, which can be detected by fluorescence spectroscopy with an excitation maximum at λ = 468 nm and an emission maximum at λ = 537 nm in acetonitrile. Three new methods based on this reaction have been developed: Direct fluorescence spectroscopy, HPLC/fluorescence, or HPLC with UV/vis detector may be selected as detection techniques. On microplates, high-throughput fluorescence spectroscopy is achieved, while HPLC/fluorescence provides lower limits of detection, and HPLC with UV/vis detection enables evaluation of the reaction with standard instrumentation. Different water samples were investigated using all detection modes, and a photometric standard procedure was successfully employed to validate the new methods with an independent technique.
- Buldt,Karst
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- N-methyl-4-hydrazino-7-nitrobenzofurazan as a new reagent for air monitoring of aldehydes and ketones
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The synthesis of N-methyl-4-hydrazino-7-nitrobenzofurazan (MNBDH) and its application as a new reagent for the determination of aldehydes and ketones are described. MNBDH reacts with carbonyl compounds in acidic media to the corresponding MNBD-hydrazones.
- Buldt, Andrea
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- Generation, basic chemistry, and detection of N-nitrosotryptophan derivatives
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N-Terminal blocked tryptophan derivatives like melatonin or tryptophan residues in peptides are easily nitrosated at the nitrogen atom of the indole ring to give the corresponding N-nitrosotryptophan derivatives. This article provides a comprehensive view of the synthesis, chemical properties, and detection methods of this class of N-nitroso compounds of potential importance in biological systems. This journal is The Royal Society of Chemistry.
- Kirsch, Michael,Korth, Hans-Gert
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- 4-(N-methylhydrazino)-7-nitro-2,1,3-benzooxadiazole (MNBDH): A novel fluorogenic peroxidase substrate
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A novel peroxide substrate with a benzooxadiazole backbone: 4-(N- methylhydrazino)-7-nitro-2,13-benzooxadiazole (MNBDH; 1) is introduced as a prototype for a new class of fluorogenic peroxide substrates. The advantages of 1 lie in its lower detection and quantification limits, a favorable red- shifted fluorescence signal, and a greater signal, and a greater signal stability after the successful reaction. The new substrate was validated by the determination of α-D-glucose in beverages.
- Meyer, Joerg,Bueldt, Andrea,Vogel, Martin,Karst, Uwe
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- Fluorescent Probes for Single-Step Detection and Proteomic Profiling of Histone Deacetylases
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Histone deacetylases (HDACs) play important roles in regulating various physiological and pathological processes. Developing fluorescent probes capable of detecting HDAC activity can help further elucidate the roles of HDACs in biology. In this study, we first developed a set of activity-based fluorescent probes by incorporating the Kac residue and the O-NBD group. Upon enzymatic removal of the acetyl group in the Kac residue, the released free amine reacted intramolecularly with the O-NBD moiety, resulting in turn-on fluorescence. These designed probes are capable of detecting HDAC activity in a continuous fashion, thereby eliminating the extra step of fluorescence development. Remarkably, the amount of turn-on fluorescence can be as high as 50-fold, which is superior to the existing one-step HDAC fluorescent probes. Inhibition experiments further proved that the probes can serve as useful tools for screening HDAC inhibitors. Building on these results, we moved on and designed a dual-purpose fluorescent probe by introducing a diazirine photo-cross-linker into the probe. The resulting probe was not only capable of reporting enzymatic activity but also able to directly identify and capture the protein targets from the complex cellular environment. By combining a fluorometric method and in-gel fluorescence scanning technique, we found that epigenetic readers and erasers can be readily identified and differentiated using a single probe. This is not achievable with traditional photoaffinity probes. In light of the prominent properties and the diverse functions of this newly developed probe, we envision that it can provide a robust tool for functional analysis of HDACs and facilitate future drug discovery in epigenetics.
- Xie, Yusheng,Ge, Jingyan,Lei, Haipeng,Peng, Bo,Zhang, Huatang,Wang, Danyang,Pan, Sijun,Chen, Ganchao,Chen, Lanfang,Wang, Yi,Hao, Quan,Yao, Shao Q.,Sun, Hongyan
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supporting information
p. 15596 - 15604
(2016/12/16)
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- Synthesis of conjugated spermine derivatives with 7-nitrobenzoxadiazole (NBD), rhodamine and bodipy as new fluorescent probes for the polyamine transport system
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The synthesis of a series of conjugated spermine derivatives with benzoxadiazole, phenylxanthene or bodipy fluorophores is described. These fluorescent probes were used to identify the activity of the polyamine transport system (PTS). N1-Methylspermine NBD conjugate 5 proved to have the optimal fluorescence characteristics and was used to show a selectivity for PTS-proficient CHO versus PTS-deficient CHO-MG cells. It can therefore be used as a tool for the selection of cells sensitive to cytotoxic compounds vectored through the PTS.
- Guminski, Yves,Grousseaud, Martial,Cugnasse, Sandrine,Brel, Viviane,Annereau, Jean-Philippe,Vispe, Stephane,Guilbaud, Nicolas,Barret, Jean-Marc,Bailly, Christian,Imbert, Thierry
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scheme or table
p. 2474 - 2477
(2009/12/25)
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- Synthesis and characterization of a new fluorescent probe for reactive oxygen species
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We report the development of a new fluorescence sensor for reactive oxygen species (ROS) based on a benzofurazan structure. The sensor, NBFhd, is initially non-fluorescent and reacts with peroxyl radicals by hydrogen transfer in an aqueous medium under neutral conditions to release the fluorescent N-methyl-4-amino-7-nitrobenzofurazan (NBF) and 1,4-benzoquinone. NBFhd shows excellent contrast and no interference in the region of cell autofluorescence and is a new tool to detect ROS in homogeneous and biological systems. This journal is The Royal Society of Chemistry.
- Heyne, Belinda,Beddie, Chad,Scaiano
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p. 1454 - 1458
(2008/01/06)
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- Effects of the substituent groups at the 4- and 7-positions on the fluorescence characteristics of benzofurazan compounds
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To develop new fluorogenic reagents having the benzofurazan structure, we investigated the effects of the substituent groups at the 4- and 7-positions of the benzofurazan skeleton on the fluorescence characteristics (fluorescence intensity, maximum excitation wavelength and maximum emission wavelength). Seventy benzofurazan compounds substituted at the 4- and 7-positions were obtained for this purpose. The Hammett substituent constant (σp) was adopted as a parameter for electronic effects by substituent groups. The study using the sum and the difference of the Hammett substituent constants (σp) at the 4- and 7-positions revealed that the highly fluorescent benzofurazan compounds were classified into two groups and that singlet excitation energies, calculated by the maximum excitation and emission wavelengths, of the benzofurazan compounds were different between these two groups. The fluorescence characteristics of benzofurazan compounds substituted at the 4- and 7-positions were empirically predictable by these relationships and σp values. A new fluorogenic reagent, 4-phenylaminosulfonyl-7-fluoro-2,1,3-benzoxadiazole, for amines was developed based on this method and applied to the amino acids analysis.
- Uchiyama, Seiichi,Santa, Tomofumi,Fukushima, Takeshi,Homma, Hiroshi,Imai, Kazuhiro
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p. 2165 - 2173
(2007/10/03)
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- Derivatization of Amines with 4-Substituted 7-Nitrobenzofurazans
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Electrophilic derivatives of 4-nitro-benzofurazan with different reactivities were used to synthesize 28 new mono- and disubstituted 4-amino-7-nitrobenzofurazans 2b, 2d, 2f-2i, 2l, 2m-2n, 3b-3f, 3h-3j, 4c-4d, 4f-4k, 4m, 4o-4p.A reaction mechanism is proposed on the basis of the differences of the reactivities and a preliminary kinetic examination.The acid character of the N-H-function in monosubstituted compounds is demonstrated by means of spectroscopical investigation of pKa-values.Data from i.r., u.v./vis, and fluorescence studies are offered.
- Heberer, H.,Kersting, H.,Matschiner, H.
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p. 487 - 504
(2007/10/02)
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