4- -7-nitrobenz-2-oxa-l,3-diazole

Heterocyclic fluorophores based on the benzoxadiazole nucleous, namely 4-nitrobenz-2-oxa-l,3-diazole (NBD) 14 derivatives/analogs, have been widely used as derivatization reagents for analysis purposes. Examples include the amino- or thiol reactive 4-fluoro-7-nitrobenz-2-oxa-l,3-diazole (NBD-F) 15 and 4-chloro-7-nitrobenz-2-oxa-1,3-diazole (NBD-C1) 16 [45-50] and the thiol-reactive /V-((2-(iodoacetoxy)ethyl)-/V-methyl)amino-7-nitrobenz-2-oxa-1,3-dia-zole (IANBD ester) 17 [51] and 7-chlorobenz-2-oxa-l,3-diazole-4-sulfonate (SBD-C1) 18 [52], NBD-F and NBD-C1 derivatives can be excited at about 470 nm by using the relatively inexpensive and reliable argon ion lasers or newer diode pumped solid state (DPSS) lasers. NBD-F has been used as a labeling tag in various capillary electrophoresis (CE) experiments for amino acids [53-57] including the monitorization of in vivo dynamics of amino acids neurotransmitters [58]. 

Figure 4 Sequences of lipidated peptides discussed in this review. The frizzled lines Indicate the building blocks used for the block coupling strategy of the solution-phase synthesis (when applicable). Abbrevations BiotAca N-(+)-Biotinyl-6-aminocaproyl MantAca N-methylanthranyl-6-aminocaproyl MIC 6-Maleimidocaproyl NBDAca N-(4-nitrobenz-2-oxa-l, 3-diazol-7-yl)-6-aminocaproyl.

List of Abbreviations ACh, acetylcholine GABA, y-aminobutyric acid lANBD, 4-[N-[2-(iodoacetoxy)-ethyl]-N-methylamino]-7-nitrobenz-2-oxa-l,3-diazole 5-IAS, 5-(iodoacetamido)salicylic acid nAChR, nicotinic acetylcholine receptor... 

When the resin was cured at 60°C and 75°C, the translational diffusion coefficient decreased nearly linearly with the cure tiffie until it decreased abruptly, at the cure time of 4000 s and 2400 s, for the resin cure at 60 °C and 75 °C, respectively. This abrupt decrease in the diffusion coefficient was presumably due to the vitrification of the resin. Diffusion measurements were also carried out on the resin mixture cured at 60°C using another fluorescent probe, 4-(N,IT-dioctyl)amino-7-nitrobenz-2-oxa-l,3-diazole. The results obtained were consistent with those obtained with the use of DilCeO). 

The extinction coefficients and quantum yields of many fluorophores depend on the microenvironment. For example, pH can affect either Cexc or (f). Fluorescein is fluorescent at pH 8 but is almost nonfluorescent at pH 6. Also there are fluorophores that are sensitive to solvent polarity. Dansyl and 7-nitrobenz-2-oxa-l,3-diazole (NBD) are much more fluorescent in hydrocarbon environments than in water. Other fluorophores are sensitive to the microviscosity. The cyanine label Cy3 is significantly more fluorescent in viscous solvents and when bound to proteins and DNA compared to when it is in water. Cyanines and rhodamines, on the other hand, are not sensitive to polarity or pH changes between 4 and 11. 

We have developed a direct and noninvasive method to determine Tg of polymers at the interface with solid substrates [54, 55]. The strategy is to use fluorescence lifetime measurements using evanescent wave excitation. Figure 15a shows PS-NBD, i.e., PS containing the dye 6-[A-(7-nitrobenz-2-oxa-l,3-diazol-4-yl)amino]hexanoic acid (NBD) [55]. The NBD fraction of PS was sufficiently low to avoid self-quenching of the dye. The NBD dye was excited with the second-harmonic generation of a mode-locked titanium sapphire laser equipped with a... 

Previously reported selective potent GABAc antagonists (S)- and (/ )-4-ACPBPA were used for the design of the fluorescent GABAc antagonists. To introduce molecular flexibility into the conjugated fluorescent ligand, Hanrahan et al. chose a linker size that varied from zero to ten carbon atoms and three different fluorophores [NMA (AT-methylanthranilic acid), 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) and 7-nitrobenz-2-oxa-l,3-diazol-4-yl chloride... 

Fluorescent probes, for experiments with retinols. A -(7-nitrobenz-2-oxa-l,3-diazol-4-yl)-l,2-dihexadecanoyl-sn-gIycero-3-phosphoethanolamine (NBD-DPPE). For experiments with retinals l-hexadecanoyI-2-(l-pyrendecanoyl)-5n-gIycero-3-phosphocholine (PY-PC) 6. Fluorescent probes can be purchased from Molecular Probes (Eugene, OR)... 

Mukherjee S, Chattopadhyay A. Membrane organization at low cholesterol concentrations a study using 7-nitrobenz-2-oxa-l,3-diazol-4-yl-labeled cholesterol. Biochemistry. 1996 35(4) 1311-1322. 

Other Names Hexanamide, (V-[2-hydroxy-l-(hydroxymethyl)-3-heptadecenyl]-6-[(7-nitro-2,l,3-benzoxadiazol-4-yl)amino]- Hexanamide, iV-[2-hydroxy-1 -(hydroxymethyl)-3-heptadecenyl]-6-[(7-nitro-4-benzofurazanyl)amino]- 2,1,3-Benzoxadiazole, hexanamide deriv. 6-((N-(7-Nitrobenz-2-Oxa-l,3-Diazol-4-yl)amino)hexanoyl)Sphingosine N-(6-[(7-nitrobenzo-2-oxa-1,3-diazo 1 -4-yl)amino] caproy 1 )-sphingosine ... 

As an example of a similar approach using in vivo SNAAR, Turcatti et aL" " incorporated a fluorescent amino acid, 3-N-(7-nitrobenz-2-oxa-l,3-diazol-4-yl)-2,3-diaminopropionic acid (NBD-Dpr), at specific sites in the tachykinin neurokinin-2 receptor, a member of the large family of seven a-helix G-protein coupled receptors (GPCRs). The expression system, Xenopus oocytes, allowed for functional assays of the receptor. Structural information was obtained by measuring the intermolecular distance between the fluorescent amino acids placed at different sites and a fluorescently labeled heptapeptide antagonist using fluorescence resonance energy transfer (FRET). 

It has been thought that membrane fusion plays an important role in cationic liposome-mediated transfection DNA is transferred into Qdoplasm via direct fusion between cationic hposomes and plasma membrane and/or fusion between cationic liposomes and endosomal membrane after being taken up by the cell through endocytosis. Thus, the effect of temperature on fusion between the polymer-modified cationic liposomes with the anionic liposomes was examined. Liposome fusion was detected by the change in resonance energy transfer efficiency from N-(7-nitrobenz-2-oxa-l,3-diazol-4-yl)phosphatidylethanolamine (NBD-PE) to lissamine rhodamine B-sulfonyl phosphatidylethanolamine (Rh-PE) due to dilution of these fluorescent lipids in the liposomal membrane. We have already shown that the fluorescence intensity ratio of NBD to Rh (R) is useful to follow membrane fusion. ... 

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