FURA

Physical Form Yellow powder Solubility Soluble in water Melting Point 250°C Absorption (Xmax) 363 nm 335 nm 

CA Index Name 5-Oxazolecarboxylic acid, 2-[6-[bis (carboxymethyl)amino]-5-[2-[2-[bis(carboxymethyl) amino]-5-methylphenoxy]ethoxy]-2-benzofuranyl]-, potassium salt (1 5) 

Staining Applications Calcium ions zinc ions cells neurons peptides proteins antibodies  

Biological Applications Calcium indicator zinc indicator identifying taste modulators measuring membrane potential treating epilepsy neurological disorders  

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Like aldopentoses aldohexoses such as d glucose are capable of forming two fura... 

Potential hydrogen bonding groups (—NH2 and C=0) point away from the fura nose ring... 

Anomeric carbon (Section 25.6) The carbon atom in a fura-nose orpyranose form that is derived from the carbonyl carbon of the open-chain form. It is the ring carbon that is bonded to two oxygens. 

In a similar manner, ketones can react with alcohols to form hemiketals. The analogous intramolecular reaction of a ketose sugar such as fructose yields a cyclic hemiketal (Figure 7.6). The five-membered ring thus formed is reminiscent of furan and is referred to as a furanose. The cyclic pyranose and fura-nose forms are the preferred structures for monosaccharides in aqueous solution. At equilibrium, the linear aldehyde or ketone structure is only a minor component of the mixture (generally much less than 1%). 

Figure 1. Original records of tension and intracellular free calcium concentration Caf ) obtained from a single mouse muscle fiber during a fatigue run (modified from Westerblad and Allen, 1991). A continuous tension record in which each vertical line represents a tetanus. B (Ca ] (measured with fura-2) and tension records obtained from the individual tetani (a, b, and c) indicated above the record in A. Three major features are illustrated 1.) the initial tension decline is accompanied by an increase in tetanic ICa li, 2.) late in fatigue the tetanic [Ca li is reduced, and 3.) the resting [Ca li increases during fatiguing stimulation (dashed line indicates resting [Ca ] in control). Stimulation periods are shown below tension records in B. From Westerblad et al., 1991, with permission from the Amer. Physiol. Society.

Intracellular calcium elevation is monitored by fluorescent chelators developed by Tsien and coworkers. These indicators are loaded into cells the same way the pH indicators are. With Quin-2 (14), one of the first such probes developed, the quantum yield increases about fourfold when Ca binds to it. The second generation of Ca probes, Indo-1 and Fura-2 (15), are now being widely used in a variety of cell types. These probes are in most cases... 

Murphy et al. showed that EPHP [25] and L2P(0)H [26] can also be used in radical C-C bond forming reactions (Scheme 8). Recently, Piettre et al. [27] used the sodium salt of hypophosphorous acid as H-donor and the subsequent phosphonyl radical as phosphonylating agent for the preparation of 3-fura-nosyl-6 -furanosylphosphinate (Scheme 9). 

Isolated chromaffin cells were maintained in suspension culture and loaded with the fluorescent calcium indicator Fura 2 as previously described (28). 2 x 10 cells/ml were added into a cuvette containing standard buffer without (dotted line) or with (full line) 2 mM calcium. At the arrow, 10" M pardaxin was added. A rise in was... 

Figure 4.7 Changes in intraceiiuiar calcium in cultured rat ventricular myocytes exposed to oxidant stress. Calcium was measured using the fluorescent probe Fura>2. The ratio of the Fura-2 fluorescence measured at 340 and 380 nm excitation is shown and this is proportional to the intracellular calcium concentration. The fast-speed traces shown (note the 3.5 s time-scale) were recorded after various durations of oxidant stress. Myocytes under control conditions (before t = 0) show spontaneous calcium transients. These transients decreased in frequency with oxidant stress until cells failed to show spontaneous activity but continued to maintain a low intracellular calcium.

Goldhaber, J.I. and Weiss, J.N. (1993). Hydrogen peroxide increases sodium-calcium exchange in patch-clamped guinea pig ventricular myocytes loaded with Fura-2. Circulation, 88(4), 724, abstract. 

Because of the double exposure, the preparation suffers from increased bleaching and photodamage. Furthermore, split-imaging on charge-coupled-device (CCD) systems (see Textbox 1) is not an option. Nevertheless, excitation ratioing may be an economic choice for laboratories that have an old Fura-imaging setup. These microscopes often allow very fast excitation switching... 

Treatment of the readily available 6-amino-5-nitrosopyrimidines 345 with a slight excess of PhI(OAc>2 or iV-iodosuccinimide in anhydrous DMF containing 3 equiv of LiH at ambient temperature resulted in a smooth and versatile formation of the corresponding fura/ano[3,4-. 

Coumarins belong to a group of compounds known as the benzopyrones, all of which consist of a benzene ring joined to a pyrone. They may also be found in nature, in combination with sugars, as glycosides. They can be categorized as simple fura-nocoumarins, pyranocoumarins, and coumarins substituted in the pyrone ring (Murray and others 1982). 

Diawara MM, Trumble JT, Quiros CF and Hansen R. 1995. Implications of distribution of linear fura-nocoumarins within celery. J Agric Food Chem 43(3) 723-727. 

FIG. 5. Maintenance of the superficial buffer barrier depends on NCX-assisted Ca2+ transport from the SR lumen to the extracellular space. (A) Rate of loss of SR Ca2+ content, measured as a caffeine transient, into Ca2+ free perfusate at room temperature. (B) Rate of decline in [Ca2+ I from an elevated level, measured as fura 2 fluorescence ratio, into Ca2+ free superfusate, which is either Na+ free or contains 10 /rM CPA or is Na+ free and contains CPA. (C) This cartoon represents a model for maintained buffering by the superficial SR of Ca2+ entry. Ca2+ taken up by SERCA is subsequently released into the SR-PM junctional space from where it is extruded by the NCX. 

Paul Do you worry about using non-ratiometric dyes here when these things are supposed to be contracting and oscillating I know people have shown waves with Fura 2, but it always makes me a little nervous when non-ratiometric dyes are used, because some of this could be artefactual. 

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