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Amplite® Fluorimetric Peroxidase (HRP) Assay Kit *Red Fluorescence*

Peroxidase is a small molecule (MW ~40 KD) that can usually be conjugated to an antibody in a 4:1 ratio. Due to its small size, it rarely causes steric hindrance problem with antibody/antigen complex formation. Peroxidase is inexpensive compared to other labeling enzymes. The major disadvantage associated with peroxidase is their low tolerance to many preservatives such as sodium azide that inactivates peroxidase activity even at low concentration. HRP conjugates are extensively used as secondary detection reagents in ELISAs, immuno-histochemical techniques and Northern, Southern and Western blot analyses. We offer this quick (10 min) HRP assay in a one-step, homogeneous, no wash assay system. The kit can be used for ELISAs, characterizing kinetics of enzyme reaction and high throughput screening of oxidase inhibitors, etc. The kit provides an optimized 'mix and read' assay protocol that is compatible with HTS liquid handling instruments.

Example protocol

AT A GLANCE

Protocol Summary
  1. Prepare HRP standards and/or test samples (50 µL)
  2. Add HRP working solution (50 µL)
  3. Incubate at room temperature for 10 - 30 minutes
  4. Monitor fluorescence intensity at Ex/Em = 540/590 nm (Cutoff = 575 nm) 
Important      Thaw all the kit components at room temperature before starting the experiment. The component A is unstable in the presence of thiols such as DTT and β-mercaptoethanol. The presence of thiols at concentration higher than 10 µM would significantly decrease the assay dynamic range. NADH and glutathione (reduced form: GSH) may interfere with the assay.

PREPARATION OF STOCK SOLUTIONS

Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles.

1. Amplite™ Red Peroxidase Substrate stock solution (100X)
Add 250 µL of DMSO (Component E) into the vial of Amplite™ Red Peroxidase Substrate (Component A) to make 100X Amplite™ Red Peroxidase Substrate stock solution. The stock solution should be used promptly. Keep from light.

2. HRP standard solution (20 U/mL)
Add 1 mL of Assay Buffer (Component C) into the vial of Horseradish Peroxidase (Component D) to make 20 U/mL of HRP standard solution.

3. H2O2 stock solution (20 mM)
Add 22.7 µL of 3% H2O2 (0.88 M, Component B) into 977 µL of Assay Buffer (Component C) to make 20 mM H2O2 stock solution . Note: The diluted H2O2 solution is not stable. The unused portion should be discarded.

PREPARATION OF STANDARD SOLUTION

For convenience, use the Serial Dilution Planner:
https://www.aatbio.com/tools/serial-dilution/11552


HRP standard
Add 1 µL of 20 U/mL HRP standard solution in 1999 µL of Assay Buffer (Component C) to get 10 mU/mL HRP standard solution (SD7). Take 10 mU/mL HRP standard solution (SD7) and perform 1:3 serial dilutions to get serially diluted HRP standards (SD6 - SD1) with Assay Buffer (Component C).

PREPARATION OF WORKING SOLUTION

Add 50 μL of 100X Amplite™ Red Peroxidase Substrate stock solution and 50 μL of 20 mM H2O2 stock solution into 4.9 mL of Assay Buffer (Component C) to make HRP working solution. Keep from light.

SAMPLE EXPERIMENTAL PROTOCOL

Table 1. Layout of HRP standards and test samples in a solid black 96-well microplate. SD= HRP Standards (SD1 - SD7, 0.01 to 10 mU/mL); BL=Blank Control; TS=Test Samples.
BLBLTSTS
SD1SD1......
SD2SD2......
SD3SD3
SD4SD4
SD5SD5
SD6SD6
SD7SD7
Table 2. Reagent composition for each well.
WellVolumeReagent
SD1 - SD750 µLSerial Dilutions (0.01 to 10 mU/mL)
BL50 µLAssay Buffer (Component C)
TS50 µLtest sample
  1. Prepare HRP standards (SD), blank controls (BL), and test samples (TS) according to the layout provided in Tables 1 and 2. For a 384-well plate, use 25 µL of reagent per well instead of 50 µL. Note: High levels of HRP (e.g., >100 mU/mL final concentration) may cause reduced fluorescence signal due to the over oxidation of Amplite™ Red (to non-fluorescent one).
  2. Add 50 µL of HRP working solution to each well of HRP standard, blank control, and test samples to make the total HRP assay volume of 100 µL/well. For a 384-well plate, add 25 µL of HRP working solution into each well instead, for a total volume of 50 µL/well.
  3. Incubate the reaction at room temperature for 10 to 30 minutes, protected from light.
  4. Monitor the fluorescence increase with a fluorescence plate reader at Excitation = 540 ± 10 nm, Emission = 590 ± 10 nm (optimal Ex/Em = 540/590 nm, Cutoff = 575 nm). Note: The contents of the plate can also be transferred to a white clear bottom plate and read by an absorbance microplate reader at the wavelength of 576 ± 5 nm. The absorption detection has lower sensitivity compared to fluorescence reading. 

Spectrum

Product family

Citations

View all 2 citations: Citation Explorer
Identification of acetylcholinesterase inhibitors using homogenous cell-based assays in quantitative high-throughput screening platforms
Authors: Li, Shuaizhang and Huang, Ruili and Solomon, Samuel and Liu, Yitong and Zhao, Bin and Santillo, Michael F and Xia, Menghang
Journal: Biotechnology Journal (2017): 1600715
Identification of acetylcholinesterase inhibitors using homogenous cell-based assays in quantitative high-throughput screening platforms
Authors: Li, Shuaizhang and Huang, Ruili and Solomon, Samuel and Liu, Yitong and Zhao, Bin and Santillo, Michael F and Xia, Menghang
Journal: Biotechnology journal (2017): 1600715

References

View all 49 references: Citation Explorer
Horseradish peroxidase-driven fluorescent labeling of nanotubes with quantum dots
Authors: Didenko VV, Baskin DS.
Journal: Biotechniques (2006): 295
Enzymatic oxidation of dipyridamole in homogeneous and micellar solutions in the horseradish peroxidase-hydrogen peroxide system
Authors: Almeida LE, Imasato H, Tabak M.
Journal: Biochim Biophys Acta (2006): 216
Recent advances in catalytic peroxidase histochemistry
Authors: Krieg R, Halbhuber KJ.
Journal: Cell Mol Biol (Noisy-le-grand) (2003): 547
Vesicular transport route of horseradish C1a peroxidase is regulated by N- and C-terminal propeptides in tobacco cells
Authors: Matsui T, Nakayama H, Yoshida K, Shinmyo A.
Journal: Appl Microbiol Biotechnol (2003): 517
Synthesis and purification of horseradish peroxidase-labeled oligonucleotides for tyramide-based fluorescence in situ hybridization
Authors: van Gijlswijk RP, van de Corput MP, Bezrookove V, Wiegant J, Tanke HJ, Raap AK.
Journal: Histochem Cell Biol (2000): 175
Page updated on November 11, 2024

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Spectral properties

Excitation (nm)

571

Emission (nm)

584

Storage, safety and handling

Certificate of OriginDownload PDF
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
UNSPSC12171501

Platform

Absorbance microplate reader

Absorbance576 ± 5 nm
Recommended plateClear bottom

Fluorescence microplate reader

Excitation540 nm
Emission590 nm
Cutoff575 nm
Recommended plateSolid black

Components

HRP dose response was measured with Amplite Fluorimetric Peroxidase Assay Kit in a black plate using a Gemini fluorescence microplate reader (Molecular Devices).
HRP dose response was measured with Amplite Fluorimetric Peroxidase Assay Kit in a black plate using a Gemini fluorescence microplate reader (Molecular Devices).
HRP dose response was measured with Amplite Fluorimetric Peroxidase Assay Kit in a black plate using a Gemini fluorescence microplate reader (Molecular Devices).