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Pierce™ Gaussia Luciferase Flash Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Gaussia Luciferase Flash Assay Kit provides researchers with the most sensitive assay for transcriptional activity of regulatory elements in mammalian cell culture media and whole cell lysate.

Features of the Gaussia Luciferase Flash Assay Kit:

Sensitive—1000 times greater sensitivity allows utilization of smaller numbers of cells
Cost effective—highest sensitivity assays result in decreased reagent consumption
Secreted luciferase—allows real-time assays and kinetic studies without destroying cells
Time-saving—assays using secreted luciferases require minimal sample handling
Automation-friendly—amenable to high throughput screens
Convenient—contains a universal cell lysis buffer and optimized flash assay reagent
Safe—allows one to perform non-radioactive assays

This Flash Assay Kit contains reagents for measuring the activity of Gaussia luciferase in mammalian cell culture media and lysates. When used with Thermo Scientific Gaussia Luc Vectors, the kit provides an extremely sensitive bioluminescent reporter assay system for secreted or intracellular detection of promoter or pathway activity. Gaussia luciferase is highly secreted into the cell culture media, allowing for live cell monitoring of reporter activity. The signal produced by Gaussia is considerably greater than signal from either firefly or Renilla luciferases assayed under similar conditions.

Includes:
Cell lysis buffer, reaction buffer and substrate

Requires:
Gaussia luciferase and luminometer or other instrument capable of monitoring luminescence, such as Thermo Scientific Luminoskan Ascent and Varioskan Flash Microplate Readers.

Applications:
• Promoter studies for analyzing cis- regulatory elements and trans-acting factors
• Drug screening
• siRNA and miRNA screening
• Multiplexed assays to study off-target effects
• Secretory pathway/protein localization reporter assays
• Signal transduction pathway analysis
• RNA splicing studies

Gaussia luciferase is a 20kDa protein from the marine copepod, Gaussia princeps. The bioluminescent enzyme is highly secreted into the cell culture media, allowing for live cell monitoring of reporter activity. Light output generated by the luciferase reaction can be correlated to the amount of Gaussia luciferase protein produced and used to determine the activity of the promoter driving Gaussia expression. The signal produced by Gaussia luciferase shows strong flash kinetics and is considerably greater than flash signals from either firefly or Renilla luciferases assayed under similar conditions. The assay kit is optimized for use with our Gaussia Luc Vectors but is fully compatible with other Gaussia luciferases and derivatives that use coelenterazine as a substrate. (For glow assays, use our Gaussia-Dura Luc Vectors.)

More Product Data
Highly sensitive multiplex luciferase reporter assays
Luciferase assays in hard-to-transfect Jurkat cells
Monitoring neuronal differentiation using multiplexed luciferase reporters
Activation of the antioxidant response pathway by pesticide chemicals
Versatile luciferases: microplate luminometers and flash luciferase assays

Z'-LYTE™ Kinase Assay Kit - Ser/Thr 4 Peptide

A coumarin and fluorescein-labeled peptide substrate which can be used for kinase screening in an antibody-free format. This peptide is based upon glycogen synthase, containing Ser-7 and a consensus seq Hyd-X-R-X-X-S⁄T-X-X, where Hyd is bulky hydrophobic, F > L > V>>A, and X is any residue.

Active Ras Pull-Down and Detection Kit (Thermo Scientific™)

The Thermo Scientific Active Ras Pull-Down and Detection Kit enables selective enrichment and detection of GTP-bound Ras GTPase through a specific protein interaction with the Raf1 protein-binding domain.

The Active Ras Pull-Down and Detection Kit includes purified GST-Raf1 Ras-binding domain (RBD), glutathione agarose resin, positive and negative controls (GTPγS and GDP, respectively), lysis/binding/washing buffer, anti-Ras antibody, SDS sample buffer, spin columns and collection tubes. The kit was validated using lysates from NIH 3T3 cells, a cell line known to have robust Ras activity.

Features of the Active Ras Pull-Down and Detection Kit:

Highly sensitive and accurate—optimized reagents, specific anti-Ras antibody and Western blot procedure ensure accurate controls and semi-quantitative results
Validated—functionally tested for Ras detection to ensure quality and performance
Compatible—effective for a variety of cell types from mouse, rat and human sources

Applications:
• Follow activation of Ras GTPase during cell differentiation, migration, division, and cytoskeletal rearrangement
• Study the role of active Ras in cancer and angiogenesis
• Monitor Ras activity after stimulation with growth factors
• Screen small molecule inhibitors for their effect on Ras activity

The Active Ras Pull-Down and Detection Kit was validated for the function and specificity of the active Ras enrichment method using cell lysates treated with GTPγS to activate endogenous Ras and compared to lysates treated with GDP to inactivate the small GTPase. GTPγS treatment trap Ras in the GTP-bound, active form, resulting in a strong signal when endogenous Ras is present. GDP treatment pushes Ras into the GDP-bound, inactive state, resulting in little to no signal, regardless of Ras protein levels. The kit is optimized for Western blot detection with an HRP-conjugated secondary antibody (Goat anti-Mouse IgG, Part No. 31430) and Thermo Scientific SuperSignal West Pico Chemiluminescent Substrate (Part No. 34080). Each kit contains sufficient components for 30 pull-down assays.

Kit components can also be used for immunofluorescent staining. Neuronal NS-1 cells were stimulated with NGF to study the spatial distribution of active Ras using the GST-RBD protein and anti-Ras antibody supplied in the kit.

Ras Background:
The Ras superfamily of GTPases, named after the rat sarcoma viral oncogene, contains many Ras isoforms, including K-Ras, H-Ras, and N-Ras. While the three isoforms are expressed at different levels in different types of cells, in general, activating mutations of at least one of these isoforms are present in ~15% of all cancers. The Ras proteins serve as initiators of intracellular signal transduction from extracellular molecules and associate with the plasma membrane via lipid modification and prenylation of its carboxy terminus. These modifications at the carboxy terminus determine the localization of Ras to distinct membrane microdomains, which dictates subsequent downstream signaling. Ras signaling pathways affect many cellular processes including proliferation, survival, vesicular trafficking and gene expression.

Signaling through Ras is central to many cellular responses, and activation of Ras is regulated by several GEF and GAP proteins. The GEF proteins mediate GTPase activation by dissociating GDP from the inactive Ras to allow binding of Ras to GTP. Conversely, GAP proteins inactivate GTPases by hydrolyzing GTP to GDP. Ras mediates downstream signaling by interacting with effector proteins, including Raf and PI3 kinase. Raf1 is a serine/threonine protein kinase that is part of the MAP kinase kinase signaling pathway that leads to the activation of ERK and p38, which influences proliferation and survival. PI3 kinase signaling results in activation of AKT and mTOR, which are central for cell growth and survival. Ras is also integral for cellular differentiation and development, including immune cell development and function.

More Product Data
Measure activation of small GTPases via their specific downstream effectors
Detection and localization of active GTPases in neuronal cell differentiation

Superoxide Dismutase (SOD) Colorimetric Activity Kit (Invitrogen™)

The Superoxide Dismutase Activity research-use-only kit is a colorimetric activity assay designed for the quantification and detection of superoxide dismutase activity in serum, plasma, cells, tissues and erythrocyte lysates.

This complete, ready-to-use kit includes clear 96-well plate(s), superoxide dismutase standard (1 Unit/vial), superoxide dismutase substrate, and other components to perform the assay. A 96-well microplate reader capable of reading optical density at 450 nm is required for use of this kit.

Performance characteristics
• Assay type: colorimetric activity kit
• Sample types: serum, plasma, cells, tissues, and erythrocyte lysates
• Sensitivity: 0.044 U/mL
• Standard curve range: 0.06 U/mL–4 U/mL
• Reactivity: species independent

Background
Short-lived and highly reactive oxygen species (ROS) such as superoxide, hydroxyl radical, and hydrogen peroxide are continuously generated in vivo. In the resting state, the balance between antioxidants and oxidants is sufficient to prevent the disruption of normal physiologic functions; however, either increases in oxidants or decreases in antioxidants can disrupt this balance giving rise to elevated levels of reactive oxygen species (ROS). The cellular levels of ROS are controlled by antioxidant enzymes and small molecule antioxidants. The major antioxidant enzymes, superoxide dismutases (SODs), including copper-zinc superoxide dismutase (Cu/ZnSOD, SOD1), manganese superoxide dismutase (MnSOD, SOD2) and extracellular superoxide dismutase (EC-SOD, SOD3), all play critical roles in scavenging superoxide .

Decreased SOD activity results in elevated level of superoxide which in turn leads to decreased NO but increased peroxynitrite concentrations. The major intracellular SOD is a 32-kD copper and zinc containing homodimer (Cu/Zn SOD). The mitochondrial SOD (MnSOD) is a manganese-containing 93-kD homotetramer that is synthesized in the cytoplasm and translocated to the inner matrix of mitochondria. This assay has been validated for serum and urine samples. Superoxide dismutases are ancient enzymes that should behave in a similar manner to the colorimetric substrate. This assay should to measure SOD activity from a wide range of sources.

Assay principle
The Superoxide Dismutase Activity kit is designed to quantitatively measure SOD activity in a variety of samples. The assay measures all types of SOD activity, including Cu/Zn, Mn, and FeSOD types. A bovine erythrocyte SOD standard is provided to generate a standard curve for the assay and all samples should be read off of the standard curve. Samples are diluted in our specially colored sample diluent and added to the wells. The substrate is added followed by Xanthine Oxidase Reagent and incubated at room temperature for 20 minutes. The xanthine oxidase generates superoxide in the presence of oxygen, which converts a colorless substrate in the detection reagent into a yellow colored product. The colored product is read at 450 nm. Increasing levels of SOD in the samples causes a decrease in superoxide concentration and a reduction in yellow product.

SOD unit definition
One unit of SOD is defined as the amount of enzyme causing half the maximum inhibition of the reduction of 1.5 mM Nitro blue tetrazolium in the presence of riboflavin at 25°C and pH 7.8.

Related links
Learn more about ELISA kits
Learn more about other immunoassays

Z'-LYTE™ Kinase Assay Kit - Ser/Thr 16 Peptide

A coumarin and fluorescein-labeled peptide substrate which can be used for kinase screening in an antibody-free format. This peptide is based upon CDC25C, containing Ser-198.

FluoReporter™ lacZ/Galactosidase Quantitation Kit (Invitrogen™)

The FluoReporter® lacZ/Galactosidase Quantitation Kit includes the β-galactosidase substrate, 3-carboxyumbelliferyl β-D-galactopyranoside that produces the blue-fluorescent hydrolysis product, 7-hydroxycoumarin-3-carboxlic acid.

Pierce™ Gaussia Luciferase Glow Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Gaussia Luciferase Glow Assay Kit provides an extremely bright and stable bioluminescence signal (half-life greater than 1 hour), especially in the presence of Gaussia-Dura luciferase reporter.

Features of the Gaussia Luciferase Glow Assay Kit:

Sensitive—highly sensitive detection of Gaussia luciferase activity
Stable—increased signal stability
Simple—does not require a luminometer with injectors
Compatible—assay reagents compatible with other Gaussia luciferases
Automation-friendly—amenable to high throughput assays
Convenient—contains a universal cell lysis buffer and optimized glow assay reagent
Safe—allows one to perform non-radioactive assays

This Pierce Luciferase Glow Assay Kit contains reagents for measuring Gaussia luciferase activity in mammalian cell culture media and lysates. When used with Thermo Scientific Gaussia-Dura Luc Vectors, the kit provides an extremely sensitive bioluminescent reporter assay system for secreted or intracellular detection of luciferase activity with extended signal stability. The light output generated by the luciferase reaction can be correlated to the amount of luciferase protein produced, which in turn is proportional to the activity of the promoter driving the luciferase expression. The kit can be used to detect the activity of any Gaussia luciferases or derivatives that use coelenterazine as a substrate.

Includes:
Cell lysis buffer, reaction buffer and substrate

Requires:
Gaussia luciferase and luminometer or other instrument capable of monitoring luminescence, such as Thermo Scientific Luminoskan Ascent and Varioskan Flash Microplate Readers.

Applications:
• Promoter studies for analyzing cis- regulatory elements and trans-acting factors
• Drug screening
• siRNA and miRNA screening
• Multiplexed assays to study off-target effects
• Secretory pathway/protein localization reporter assays
• Signal transduction pathway analysis
• RNA splicing studies

Gaussia luciferase is a 20kDa protein from the marine copepod, Gaussia princeps. The bioluminescent enzyme is highly secreted into the cell culture media, allowing for live cell monitoring of reporter activity. Light output generated by the luciferase reaction can be correlated to the amount of Gaussia luciferase protein produced and used to determine the activity of the promoter driving Gaussia expression. The signal produced by Gaussia luciferase shows strong flash kinetics and is considerably greater than flash signals from either firefly or Renilla luciferases assayed under similar conditions.

The Gaussia-Dura gene used in the Thermo Scientific Gaussia-Dura Luc Vectors is derived from the wild type Gaussia gene and provides equally bright but more stable light output. The Gaussia Glow Assay Kit reagent yields a Gaussia-Dura luciferase reaction with glow-type kinetics and is recommended for luminometers without injectors or for applications requiring batch processing of samples.

Z'-LYTE™ Kinase Assay Kit - Ser/Thr 5 Peptide

A coumarin and fluorescein-labeled serine⁄threonine peptide substrate which can be used for kinase screening in an antibody-free format.

DetectaGene™ Green CMFDG lacZ Gene Expression Kit (Invitrogen™)

The DetectaGene™ Green lacZ Gene Expression Kit includes a fluorescein-based β-galactose derivative that has been chemically modified to include a mildly thiol-reactive chloromethyl group. Once inside a cell, the DetectaGene™ substrate undergoes two reactions: 1) its two galactose moieties are cleaved by intracellular β-galactosidase and 2) either simultaneously or sequentially, its chloromethyl moiety reacts with glutathione and possibly other intracellular thiols to form a membrane-impermeant, peptide-fluorescent dye adduct.

beta-Galactosidase Assay Reagent (Thermo Scientific™)

The Thermo Scientific Mammalian β-Galactosidase Assay Reagent is a component of the Mammalian β-Galactosidase Assay Kit, which provides a simple colorimetric method for lysing cultured mammalian cells and measuring beta-Gal activity.

The Assay Reagent and Kit comprise a simple and versatile assay system for measuring β-galactosidase activity. Mammalian cells grown on a plate may be lysed and tested for β-galactosidase activity by adding a single, all-in-one lysis-and-assay solution. Alternatively, the included Thermo Scientific M-PER Mammalian Protein Extraction Reagent may be used to prepare lysate from washed adherent or pelleted cells, and then a portion of the lysate used to quantitate the β-Gal activity. With M-PER Reagent, there is no need to scrape cells or to perform freeze-thaw cycles. The remaining lysates prepared with M-PER Reagent may be used for applications such as reporter assays (luciferase, β-galactosidase and chloramphenical acetyltransferase), protein kinase assays (PKA, PKC, and Tyrosine Kinase), immunoassays (Western blot, ELISA, RIA) and protein purification.

Features of the Thermo Scientific Mammalian β-Galactosidase Assay Kit (assay reagent and stop solution):

• Choose stand-alone assay reagent or complete kit for cell lysis and detection
• Colorimetric assay easily measured in a plate reader or spectrophotometer (405nm)
• Adaptable to 96-well microplates or tube assay formats
• Perform homogeneous screening assays or measure activity secondarily after cell lysis
• Also compatiible with prepared lysates from other species such as bacteria

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Mammalian beta-Galactosidase Assay Kit
beta-Galactosidase Assay Stop Solution

Pierce™ Firefly Luc One-Step Glow Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Firefly One-Step Luc Glow Assay Kit measures firefly luciferase activity in mammalian cell culture using a single reagent-addition step, making it ideal for high-throughput screening (HTS) applications.

Features of the Firefly One-Step Luc Glow Assay Kit:

Sensitive—highly sensitive detection of firefly luciferase activity
Odorless—reagents have no foul or toxic odor, eliminating the need to work in a fume hood
Convenient—one-step, mix-and-read protocol; no additional reagents required
Stable—increased signal half-life and stability compared to flash assays
Simple—does not require a luminometer with injectors
Automation-friendly—amenable to high throughput assays

This glow-type luciferase assay kit is designed for use with cultured mammalian cells that are transfected with vectors expressing the appropriate firefly luciferase reporter enzyme. Several features make the kit especially suitable for luminometers without injectors and for high-throughput screening (HTS) applications. The convenient, one-step, homogenous protocol minimizes handling steps to support the use of automation. Simply combine the supplied substrate solution and assay buffer to make a single working solution, and then add it to microplate wells containing the transfected, treated cells. The stable signal output (glow) of this system provides flexibility with regard to incubation time. When used with Thermo Scientific Firefly Luc Plasmids, the kit provides a highly sensitive bioluminescent reporter assay system for the detection of promoter or pathway activity.

Includes:
Assay buffer and substrate solution (100X)

Requires:
Firefly luciferase and luminometer or other instrument capable of monitoring luminescence, such as Thermo Scientific Luminoskan Ascent and Varioskan Flash Microplate Readers.

Applications:
• Promoter studies for analyzing cis- and trans-acting regulatory elements
• Drug screening
• siRNA and miRNA screening
• Multiplexed assays to study off-target effects
• Protein localization reporter assays
• Signal transduction pathway analysis

Firefly luciferase is a 62kDa protein produced in nature by several species of the Lampyridae family of beetles, which includes the genera Photinus and Luciola. Thermo Scientific Red Firefly Luciferase has an emission range of 560-700nm (λmax = 613nm). Bioluminescent signal from firefly luciferase originates from the oxidation of D-Luciferin. Light output captured using a luminometer can be correlated with the amount of firefly luciferase protein produced and used to determine the activity of the promoter driving firefly luciferase expression. Firefly luciferase bioluminescence provides researchers with a non-radioactive assay for measuring transcriptional activity of regulatory elements. Firefly luciferase reporter activity can be used to determine promoter activity, to study upstream pathway activity in the cell, or to determine effect of activators or inhibitors.

Pierce™ Renilla-Firefly Luciferase Dual Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Renilla-Firefly Luciferase Dual Assay Kit provides the necessary reagents to simultaneously detect intracellular Renilla and Red Firefly luciferase activity in mammalian whole cell lysates.

Features of the Renilla-Firefly Luciferase Dual Assay Kit:

Simultaneous—concurrent, filter-based, wavelength-separated detection of two luciferase activities
Sensitive—measure Green Renilla and red firefly luciferase activities in the same sample
Fast—no quenching step required, unlike in traditional sequential dual assays
Multiplex—capable of quantitating two cellular activities in the same sample(s)

The Pierce Renilla-Firefly Luciferase Dual Assay Kit is a highly sensitive assay that allows for the simultaneous detection of Green Renilla and Red Firefly luciferase activity. Green Renilla luciferase acts as an experimental reporter with constitutively active red firefly as a normalization control. As shown in the animation video below, this reporter-and-control combination enables simultaneous monitoring of experimental reporter and control luciferase activities in a single-read assay without the need for two-step addition of substrate reagents or quenching. The assay working solution contains substrates for both luciferases, and the reactions occur simultaneously with flash-type kinetics. The resulting luminescent signals are spectrally resolvable using filters. In a single sample, researchers can assay transcriptional activity of regulatory elements, signal transduction pathways, and effects of activators or inhibitors.

Includes:
Cell lysis buffer, reaction buffer, and substrates coelenterazine and D-luciferin

Requires:
Green Renilla and Red Firefly luciferase reporters; Filter sets at 525nm±20nm for Green Renilla Luc and 615 to 675nm for Red Firefly Luc. Luminometer or other instrument capable of monitoring luminescence, such as Thermo Scientific Luminoskan Ascent and Varioskan Flash Microplate Readers; Injector required for assessing more than 24 wells at a time.

Applications:
• Study two regulatory elements at the same time
• Monitor two signaling pathways simultaneously
• Enable studying more than one target per screen (e.g. off-target effects)

Green Renilla produces brighter bioluminescent signal than firefly and native Renilla luciferases. The bioluminescent signal (λmax= 535nm) produced by Green Renilla luciferase protein results from the oxidation of coelenterazine. The second assay uses red firefly luciferase, which is a mutant form of the Japanese firefly luciferase Luciola cruciata. This luciferase produces a red-shifted emission spectrum (λmax= 613nm) that results from the oxidation of D-luciferin in the presence of ATP.

More Product Data
Simultaneous dual-emission detection of luciferase reporter assays

Related Products
Pierce™ Renilla-Firefly Luciferase Dual Assay Kit

EnzChek™ Protease Assay Kit, red fluorescence, 100-1000 assays (Invitrogen™)

The EnzChek® Protease Assay Kit, red fluorescence, is a fast, simple, and direct fluorescence-based assay for detecting metallo-, serine, acid, and sulfhydryl proteases. The accompanying increase in fluorescence, which can be measured with a fluorescence microplate reader, is proportional to protease activity.

See our complete line of Fluorescence Microplate assays.

• Generalized mechanism allows for measurement of a variety of proteases
• Can be used to continuously measure protease kinetics
• Excitation/emission similar to Texas Red® dye (589/617 nm)

This EnzChek® Protease Assay Kit contains a casein derivative that has been extensively labeled with the red-fluorescent BODIPY® TR-X dye, which results in a quenching of the fluorescent dye. Protease-catalyzed hydrolysis releases the highly-fluorescent BODIPY® TR-X dye-labeled peptides, allowing for quantitative detection of protease activity in solution. The red-fluorescent BODIPY® TR-X dye has excitation and emission spectra similar to those of the Texas Red® fluorophore.

EnzChek™ Phosphatase Assay Kit (Invitrogen™)

Using the EnzChek Phosphatase Assay Kit continuous monitoring of phosphatase activity, even at neutral or acidic pH, can be achieved. The kit contains Molecular Probes' patented 6,8-difluoro-4-methylumbelliferyl phosphate (DiFMUP) substrate (D6567). DiFMUP is about 100 times more sensitive than 4-methylumbelliferyl phosphate (MUP) for the detection of prostatic acid phosphatase at pH 5.5. The kit is perfect for the continuous assay of prostatic acid phosphatase, protein phosphatase 1 or almost any other phosphatase that can be assayed with nonprotein-based substrates such as MUP or 4-nitrophenyl phosphate (PNPP). Each kit contains a sufficient amount of substrate for ~1000 assays, using a reaction volume of 100 µL per assay. Fluorescence (excitation/emission maxima ~358/455 nm) can be measured in a fluorescence microplate reader or a standard fluorometer.

Amplex™ Acetylcholine/Acetlycholinesterase Assay Kit (Invitrogen™)

The Amplex® Red Acetylcholine/Acetylcholinesterase Assay Kit provides an ultrasensitive method for detecting acetylcholinesterase (AChE) activity in a fluorescence microplate reader or fluorometer.

See our complete line of Fluorescence Microplate assays.

• Detect AChE activity levels as low as 0.002 U/mL in one hour
• Detect acetylcholine levels as low as 0.3 µM using excess AChE
• Achieve detection ranges of 0.3 µM to 100 µM acetylcholine
• Format allows for multiple time point measurements
• Designed for minimal autofluorescence interference

AChE activity is monitored indirectly using 10-acetyl-3,7-dihydroxyphenoxazine (Amplex® Red reagent), a sensitive fluorogenic probe for hydrogen peroxide. AChE converts the acetylcholine substrate to choline, which is then oxidized by choline oxidase to betaine and hydrogen peroxide. In the presence of horseradish peroxidase, hydrogen peroxide reacts with the Amplex® Red reagent in a 1:1 stoichiometric ratio to generate the highly fluorescent product resorufin.

Because resorufin has absorption and fluorescence emission maxima of approximately 571 nm and 585 nm, respectively, there is little interference from autofluorescence in most biological samples. Experiments with purified AChE from electric eel indicate that the Amplex® Red Acetylcholine/Acetylcholinesterase Assay Kit can detect AChE levels as low as 0.002 U/mL using a reaction time of one hour. By providing an excess of AChE in the assay, the kit can also be used to detect acetylcholine levels as low as 0.3 µM, with a range of detection from 0.3 µM to 100 µM acetylcholine.

Use Amplex® Red Assays for a Broad Range of Investigations
A wide variety of validated Amplex® Red assays are available for studying cell signaling and lipids, neurobiology, inflammation and immune function, and metabolism. We also offer Amplex® UltraRed Reagent (Cat. No. A36006), a second-generation reagent providing greater sensitivity and brighter fluorescence, and the Amplex® Red/UltraRed Stop Reagent (Cat. No. A33855). The Amplex® Red/UltraRed Stop Reagent provides convenience and control by allowing the fluorescence signal-generating reaction to be terminated at a user-determined time point. After addition of the stop reagent, the fluorescence signal remains stable for at least three hours. Custom assay design and packaging are also available.