The Brightest and Most Sensitive Red Fluorescent Ca2+ Indicator
Calcium acts as a universal second messenger in a variety of cells.
Since the 1920s, scientists have attempted to measure Ca2+, but few were successful due to limited availability of Ca2+ probes. The first reliable measurements of Ca2+ were performed by Ridgway and Ashley by injecting the photoprotein aequorin into the giant muscle fiber of the barnacle. Subsequently, in the 1980s, Tsien and colleagues produced a variety of fluorescent indicators. Among them the rhodamine-based Ca2+ reagents (such as Rhod-2) have been the most valuable longer wavelength dye for measuring Ca2+ with red fluorescence.
has been the most popular red fluorescent Ca2+ indicator, its mitochondrial localization and high basal Ca2+ signal in cells have severely limited its cellular applications. In addition, the less optimal excitation of Rhod-2 at 488 nm makes it less robust to use with some instruments (such as FLIPR™) that have only 488 nm excitation light source. Quest Rhod-4™
serial calcium detection reagents have been developed to address these limitations of Rhod-2. The absorption and emission peaks of Quest Rhod-4™ reagents are 530 nm and 555 nm, respectively. Although Rhod-4 has maximum absorption at 530 nm, its absorption at 488 nm is quite strong. It is quite unique that Quest Rhod-4™ can be well excited with an argon ion laser at 488 nm besides the longer wavelength 514 nm, 532 nm and 546 nm excitations. Quest Rhod-4™ emits fluorescence (at wavelengths 555 nm) that increases with increasing Ca2+. Quest Rhod-4™ is determined to undergo a >200-fold increase in fluorescence upon binding Ca2+. Because the range of increase in Ca2+ in many cells after stimulation is generally 5- to10-fold, Quest Rhod-4™ is an excellent probe to use with high sensitivity in this region. The Kd of Quest Rhod-4™ is estimated to be 525 nM (22°C, pH 7.0 –7.5), but this value may be significantly influenced by pH, viscosity, and binding proteins in vivo
- Longer Wavelengths: excitations @ 488, 514, 532 & 546 nm; emission @ ~555 nm.
- No Wash Required and No Quencher Interference with Your Targets.
- Robust Performance: enable calcium assays that are impossible with Rhod-2 AM.
- Strongest Signal Intensity: 4 times brighter than Rhod-2 AM in fluorescence imaging applications.
- Larger Assay Window: 10 times better than Rhod-2 AM for HTS applications.
| Cat # || Product Name || Unit Size |
|ABD-21121 || Quest Rhod-4™, AM || 5x50 µg |
|ABD-21123 || Quest Rhod-4™, AM || 20x50 µg |
|ABD-21128 || Quest Rhod-4™, sodium salt || 5x50 µg |
|ABD-36331 || Screen Quest™ Rhod-4 NW Calcium Assay Kit *Medium Removal* || 10 Plates |
|ABD-36334 || Screen Quest™ Rhod-4 NW Calcium Assay Kit *1% FBS Growth Medium * || 10 Plates |
Calcium Detection Reagents
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