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Pierce™ Streptavidin Poly-HRP (Thermo Scientific™)

Thermo Scientific Pierce Streptavidin Poly-HRP conjugate is biotin-binding protein conjugated with polymers of horseradish peroxidase, enabling signal amplification and detection of biotinylated antibodies for IHC and other methods.

Features of Streptavidin Poly-HRP:

High sensitivity—detect low-abundant targets (low picogram-femtogram range) with high signal-to-noise ratios
Robust—consistent manufacturing and purification to eliminate low- and un-conjugated molecules for minimal background and high sensitivity
Flexible—compatible with chromogenic, fluorogenic and chemiluminescent substrates
Versatile—compatible with ELISA, Western blotting and immunohistochemistry (IHC)
Easy to use—can be directly substituted into immunoassays and other detection assays
Convenient—ready-to-use stabilized liquid format stored at 4°C
Cost effective—requires less conjugate per assay and standard HRP conjugates

Streptavidin Poly-HRP conjugate is designed to deliver the highest sensitivity and low background in immunoassays where sample volume is limited or when the target molecule is present at low levels. Streptavidin Poly-HRP is purified to remove unconjugated streptavidin molecules that reduce signal intensity by competing for binding sites with horseradish peroxidase (HRP)-conjugates molecules. In addition, the conjugate is devoid of HRP monomers that can cause background signal. The Pierce Streptavidin Poly-HRP is compatible with chromogenic, fluorogenic and chemiluminescent HRP substrates used in ELISA, Western blotting, immunohistochemistry (IHC) and nucleic acid hybridization assays.

Several forms of streptavidin-HRP conjugates are available that do not contain polymerized HRP (poly-HRP) and are suitable for most biotin detection assays. These and other commonly used HRP-conjugated antibodies and biotin-binding proteins are limited to one to three HRP molecules per protein in order to maintain functionality of the conjugate. This molar ratio of conjugation is effective in routine experiments but may lack the sensitivity required for detecting targets present in low picogram to femtogram amounts without the use of additional steps to amplify the signal.

When a higher degree of signal amplification is needed with standard HRP conjugates, methods such as peroxidase anti-peroxidase (PAP) systems or avidin-biotin complexes (ABC) can be used. However, these methods increase the cost of the assay and the number of steps that must be optimized. Pierce Streptavidin Poly-HRP circumvents such problems because it uses polymers of HRP molecules that are conjugated to streptavidin in a proprietary manufacturing process that increases the molar ratio of HRP on the conjugate while maintaining functionality. The increased molar ratio of HRP molecules to streptavidin results in more HRP molecules being available per binding event to react with the substrate. Therefore, Pierce Streptavidin Poly-HRP provides substantial signal amplification over other HRP-conjugates, eliminating the need for additional steps and saving time and expense.

As with all immunoassays, optimization is required to achieve the best signal-to-noise ratio. Switching to higher sensitivity substrates and conjugates can reveal more desired signal as well as background signal. If this occurs, follow standard primary and secondary dilution techniques or perform blocking buffer optimization.

Streptavidin (Invitrogen™)

Streptavidin is a bacterially derived biotin-binding protein that reportedly exhibits less nonspecific binding than avidin.

Streptavidin is unlabeled, unconjugated, and provided as a lyophilized powder.

Qdot™ 625 Streptavidin Conjugate (Invitrogen™)

Qdot® 625 Streptavidin Conjugate comprises a biotin-binding protein (streptavidin) covalently attached to a fluorescent label (Qdot® nanocrystal). Streptavidin has a very high binding affinity for biotin, and a conjugate of streptavidin is commonly used together with a conjugate of biotin for specific detection of a variety of proteins, protein motifs, nucleic acids, and other molecules (for example, a biotinylated primary antibody bound to a protein target can be detected with a fluorescently labeled streptavidin). Strategies similar to this are used in many detection protocols including western blots, flow cytometry, imaging and microscopy, and microplate assays, and are also used in purification workflows to achieve targeted fractionation. Qdot® nanocrystal conjugates are provided as 1 µM solutions.

Important Features of Qdot® Streptavidin Conjugates:

• Streptavidin Qdot® 625 conjugate has emission maxima of ~625 nm
• Approximately 5 to 10 streptavidins per Qdot® nanocrystal
• Extremely photostable and bright fluorescence
• Efficiently excited with single-line excitation sources
• Narrow emission, large Stokes shift
• Available in multiple colors
• Ideal for western blots, flow cytometry, imaging and microscopy, microplate assays and more

Properties of Qdot® Nanocrystals
The Qdot® streptavidin conjugate is the size of a large macromolecule or protein (~15–20 nm) and represents the brightest class of streptavidin detection reagents. Qdot® streptavidin conjugates are made from a nanometer-scale crystal of a semiconductor material (CdSe), which is coated with an additional semiconductor shell (ZnS) to improve the optical properties of the material. The Qdot® 705 and Qdot® 800 streptavidin conjugates, which include CdSeTe, are made in a similar fashion. This core-shell material is further coated with a polymer shell that allows the materials to be conjugated to biological molecules and to retain their optical properties.

Other Fluorescent Conjugates of Streptavidin are Available
We offer several other Qdot® colors or try the Qdot® Streptavidin Sampler Kit, containing Qdot® streptavidin conjugates in six colors 525, 565, 585, 605, 655, and 705. In addition to nanocrystal conjugates, we offer a wide range of streptavidins conjugated to Alexa Fluor® dyes, Oregon Green® dye, enzyme conjugates, and traditional fluorophores like Texas Red® dye, fluorescein (FITC) and more.

Find Biotinylated Conjugates
We offer an extensive line of biotinylated conjugates for use in biotin-streptavidin detection strategies.

• Use the primary antibody search tool to find biotinylated primary antibodies
• Use the secondary antibody selector tool to find biotinylated secondary antibodies and biotinylated anti-dye and anti-hapten antibodies

Blocking Endogenous Biotin
Naturally occurring biotins can interfere with biotin-streptavidin detection schemes. For experiments involving fixed and permeabilized cells, try our Endogenous Biotin-Blocking Kit to minimize this interference.

Related Links:
Learn more about Avidin-Biotin Detection
Learn more about Qdot® Nanocrystals

Qdot™ 565 Streptavidin Conjugate (Invitrogen™)

Qdot® 565 streptavidin conjugate comprises a biotin-binding protein (streptavidin) covalently attached to a fluorescent label (Qdot® nanocrystal). Streptavidin has a very high binding affinity for biotin, and a conjugate of streptavidin is commonly used together with a conjugate of biotin for specific detection of a variety of proteins, protein motifs, nucleic acids, and other molecules (for example, a biotinylated primary antibody bound to a protein target can be detected with a fluorescently labeled streptavidin). Strategies similar to this are used in many detection protocols including western blots, flow cytometry, imaging and microscopy, and microplate assays, and are also used in purification workflows to achieve targeted fractionation. Qdot® nanocrystal conjugates are provided as 1 µM solutions.

Important Features of Qdot® Streptavidin Conjugates:
Streptavidin Qdot® 565 conjugate has emission maxima of ~565 nm
Approximately 5 to 10 streptavidins per Qdot® nanocrystal
Extremely photostable and bright fluorescence
Efficiently excited with single-line excitation sources
Narrow emission, large Stokes shift
Available in multiple colors
Ideal for western blots, flow cytometry, imaging and microscopy, microplate assays and more

Properties of Qdot® Nanocrystals
The Qdot® streptavidin conjugate is the size of a large macromolecule or protein (~15–20 nm) and represents the brightest class of streptavidin detection reagents. Qdot® streptavidin conjugates are made from a nanometer-scale crystal of a semiconductor material (CdSe), which is coated with an additional semiconductor shell (ZnS) to improve the optical properties of the material. The Qdot® 705 and Qdot® 800 streptavidin conjugates, which include CdSeTe, are made in a similar fashion. This core-shell material is further coated with a polymer shell that allows the materials to be conjugated to biological molecules and to retain their optical properties.

Other Fluorescent Conjugates of Streptavidin are Available
We offer several other Qdot® colors or try the Qdot® Streptavidin Sampler Kit, containing Qdot® streptavidin conjugates in six colors 525, 565, 585, 605, 655, and 705. In addition to nanocrystal conjugates, we offer a wide range of streptavidins conjugated to Alexa Fluor® dyes, Oregon Green® dye, enzyme conjugates, and traditional fluorophores like Texas Red® dye, fluorescein (FITC) and more.

Find Biotinylated Conjugates
We offer an extensive line of biotinylated conjugates for use in biotin-streptavidin detection strategies.
• Use the primary antibody search tool to find biotinylated primary antibodies
• Use the secondary antibody selector tool to find biotinylated secondary antibodies and biotinylated anti-dye and anti-hapten antibodies

Blocking Endogenous Biotin
Naturally occurring biotins can interfere with biotin-streptavidin detection schemes. For experiments involving fixed and permeabilized cells, try our Endogenous Biotin-Blocking Kit to minimize this interference.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Related Links:

Learn more about Avidin-Biotin Detection

To learn more about Qdot® Nanocrystals

Streptavidin, Alexa Fluor™ 555 Conjugate (Invitrogen™)

Alexa Fluor® 555 streptavidin comprises a biotin-binding protein (streptavidin) covalently attached to a fluorescent label (Alexa Fluor® dye). Streptavidin has a very high binding affinity for biotin, and a conjugate of streptavidin is commonly used together with a conjugate of biotin for specific detection of a variety of proteins, protein motifs, nucleic acids, and other molecules (for example, a biotinylated primary antibody bound to a protein target can be detected with a fluorescently labeled streptavidin). Strategies similar to this are used in many detection protocols including western blots, flow cytometry, imaging and microscopy, and microplate assays. Alexa Fluor® dye streptavidin conjugates are supplied as 1 mg lyophilized product or in 0.5 mL volumes of a 2 mg/mL solution.

Important Features of Alexa Fluor® 555 Streptavidin Conjugates:
Alexa Fluor® 555 streptavidin conjugate has Ex/Em maxima of ~ (555/565)
Bright, photostable fluorescence
High solubility in aqueous solutions
Available in multiple colors
Ideal for western blots, flow cytometry, imaging and microscopy, microplate assays and more

Properties of Alexa Fluor® Dyes
Alexa Fluor® dyes are organic fluorescent dyes developed for better performance in imaging and other labeling protocols and exhibit improved photostability and brightness and improved solubility in aqueous solutions. Available in a broad range of colors, these dyes are a good choice for most imaging applications.

Blocking Endogenous Biotin
Naturally occurring biotins can interfere with biotin-streptavidin detection schemes. For experiments involving fixed and permeabilized cells, try our Endogenous Biotin-Blocking Kit to minimize this interference.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Related Links:

Learn more about Avidin-Biotin Detection

Learn more about Alexa Fluor® Dyes

Find out about other Labeled Streptavidin Conjugates

Read Avidin and Streptavidin Conjugates-Section 7.6 in the Molecular Probes Handbook

Streptavidin Protein, AP (Thermo Scientific™)

Thermo Scientific™ Streptavidin, Alkaline Phosphatase Conjugate includes streptavidin in a purified form, conjugated to alkaline phosphatase for substrate based detection.

Streptavidin is a biotin-binding protein originally isolated from Streptomyces avidinii. In contrast to avidin, streptavidin has no carbohydrate and has a mildly acidic pI of 5. Thermo Scientific streptavidin products use a recombinant form of streptavidin having a mass of 53,000 daltons and a near-neutral pI. Streptavidin is a tetrameric protein, with each subunit binding one molecule of biotin with affinity similar to that of avidin. Guanidinium chloride will dissociate avidin and streptavidin into subunits, but streptavidin is more resistant to dissociation.

Streptavidin, Alkaline Phosphatase Conjugate enables detection of biotinylated antibodies and other probes in a variety of standard assay methods, including western blotting, ELISA, immunohistochemistry, and fluorescence imaging.

Recommended concentrations: ELISA (0.1 µg/mL), immunofluorescence (assay dependent), western blot (2 µg/mL)

eBioscience™ Streptavidin Super Bright 645 Conjugate (Invitrogen™)

eBioscience Streptavidin Super Bright 645 is a streptavidin-fluorochrome conjugate for indirect staining protocols to detect biotinylated primary antibodies in flow cytometry. Super Bright dyes are polymer-based fluorophores that are excited by the violet laser (405 nm) and emit fluorescence at the wavelength indicated in their name. They are optimized for use in flow cytometry and allow for use of additional channels with violet excitation. Super Bright dyes are fully compatible with other commonly used fluorescent molecules, eBioscience buffers and fixatives, viability stains, and reagents.

Super Bright 645 is a tandem dye that can be excited with the violet laser line (405 nm) and emits at 645 nm. We recommend using a 660/20 bandpass filter or equivalent. Please make sure that your instrument is capable of detecting this fluorochrome.

Applications tested
Streptavidin Super Bright 645 Conjugate has been tested by flow cytometric analysis to detect biotinylated primary antibodies. The amount of this conjugate that will stain a cell sample in a final volume of 100 μL is less than or equal to 0.125 μg. Cell number should be determined empirically but can range from 105 to 108 cells/test. It is recommended that the streptavidin be carefully titrated for optimal performance in the assay of interest.

Samples can be stored in IC Fixation Buffer or 1-step Fix/Lyse Solution for up to three days in the dark at 4°C with minimal impact on brightness and FRET efficiency/compensation. Clone specific performance after fixation should be determined empirically.

When using two or more Super Bright dye-conjugated antibodies in a staining panel, it is recommended to use Super Bright Complete Staining Buffer to minimize any non-specific polymer interactions. Please refer to the datasheet for Super Bright Complete Staining Buffer for more information.

Super Bright polymer dyes are sold under license from Becton, Dickinson and Company.

Streptavidin - FITC (Invitrogen™)

Reactivity: FITC-SA will react with biotin.

eBioscience™ Streptavidin APC Conjugate (Invitrogen™)

The streptavidin fluorochrome conjugates are commonly used in indirect staining protocols to detect biotinylated primary antibodies in flow cytometry. Streptavidin binds to biotin with high affinity.

Laser
Red Laser

Emit
660 nm

Excite
633 - 647 nm

Reported Application
Flow Cytometric Analysis

eBioscience™ Streptavidin APC-eFluor™ 780 Conjugate (Invitrogen™)

The streptavidin fluorochrome conjugates are commonly used in indirect staining protocols to detect biotinylated primary antibodies in flow cytometry. Streptavidin binds to biotin with high affinity.

Laser
Red Laser

Emit
780 nm

Excite
633 - 647 nm

Reported Application
Flow Cytometric Analysis

Streptavidin, fluorescein conjugate (Invitrogen™)

Searching for superior alternatives to fluorescein? Our Alexa Fluor Dye Series offers everything you're looking for and more.

Streptavidin, horseradish peroxidase conjugate (Invitrogen™)

The streptavidin, horseradish peroxidase (HRP) conjugate can be used to detect biotin in a signal amplification scheme in conjunction with chromogenic substrates or fluorogenic HRP substrates, such as the tyramide signal amplification (TSA) technology.

HRP-Conjugated Streptavidin (Thermo Scientific™)

HRP-Conjugated Streptavidin consists of streptavidin protein that is covalently conjugated to horseradish peroxidase (HRP) enzyme (RZ > 3.0). Streptavidin binds to biotin and the conjugated HRP provides enzyme activity for detection using an appropriate substrate system. This particular product has been used primarily in sandwich ELISA applications to provide consistent measurement of biotinylated detection antibodies.

Features of HRP-Conjugated Streptavidin :

Product Number: N100
Size: 0.25 mL
Concentration: 1.25 mg/mL
Formulation: Provided in a conjugate stabilizer containing 0.1% ProClin Compound as a preservative.
Storage: Shipped on cold packs. Store at 2-8°C upon receipt. Protect from exposure to light. Stable until expiration date if stored under these conditions.
Application: ELISA: to be used with biotin-labeled detection antibodies. Recommended dilution range is from 1:4,000 to 1:20,000. The optimal dilution must be determined empirically for each specific application. Prepare dilutions immediately before use.

Streptavidin Protein (Thermo Scientific™)

Thermo Scientific™ Pierce™ Streptavidin is a purified unconjugated recombinant protein.

Features include:
Recombinant streptavidin—high-quality protein, 53 kDa, pI = 6.8–7.5
Pure protein—choose pure, unconjugated protein for biotin blocking and controls

Purified recombinant streptavidin enables detection of biotinylated antibodies and other probes in a variety of standard assay methods, including western blotting, ELISA, immunohistochemistry, and fluorescence imaging. Purified streptavidin is supplied lyophilized in phosphate-based buffer for immediate reconstitution with water.

Streptavidin is a biotin-binding protein originally isolated from Streptomyces avidinii. In contrast to avidin, streptavidin has no carbohydrate and has a mildly acidic pI of 5. Pierce™ streptavidin products use a recombinant form of streptavidin having a mass of 53,000 daltons and a near-neutral pI. Streptavidin is a tetrameric protein, with each subunit binding one molecule of biotin with affinity similar to that of avidin. Guanidinium chloride will dissociate avidin and streptavidin into subunits, but streptavidin is more resistant to dissociation.

Applications: ELISA (assay dependent), western blot (assay dependent)

Related products
Pierce™ Streptavidin, Horseradish Peroxidase Conjugated
Pierce™ Streptavidin, Alkaline Phosphatase Conjugated
Pierce™ Streptavidin, Maleimide-Activated
Pierce™ Streptavidin, Hydrazide-Activated

Qdot™ 655 ITK™ Streptavidin Conjugate Kit (Invitrogen™)

The Qdot® 655 ITK™ Streptavidin Conjugate Kit provides the Qdot® streptavidin conjugate as 250 µL of a 2 µM solution. Unlike the Qdot® streptavidin conjugates, the Qdot® ITK™ streptavidin conjugates have the streptavidin covalently attached to the inner amphiphilic coating without a PEG linker. These Qdo® conjugates can be used for binding biotinylated probes. The kit also includes 30 mL of Qdot® incubation buffer.