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PE Conjugated Antibodies & Reagents

Phycoerythrin (PE) is a large (240 kDa) light-harvesting phycobiliprotein found in red algae, which transfers energy to chlorophyll to support oxidative photosynthesis. It produces an intense red-orange fluorescence as a result of its high extinction coefficient (1.96 x 106 M-1 cm-1) and quantum yield (0.84), which make it one of the brightest known fluorophores. These properties of PE, combined with a large Stokes shift, have led to it being widely used for flow cytometry and fluorescence-activated cell sorting (FACS).

We offer a broad range of PE-conjugated primary and secondary antibodies, as well as antibodies conjugated to PE tandem dyes, including PE/CY7, PE/CY5.5, and PE/Texas Red®. Our product portfolio also includes PE-conjugated isotype controls and PE-streptavidin conjugates.

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Frequently Asked Questions

PE has an excitation maximum of 566 nm (with a secondary maximum at 496 nm) and an emission maximum of 575 nm. It can be excited by laser lines spanning 488 to 561 nm and detected using an appropriate filter set (e.g., 586/14 nm).

R-PE and B-PE are named after the organisms that produce them: R-PE is produced by complex Rhodophyta (red algae) while B-PE is produced by Bangiophyceae (primitive filamentous Rhodophyta). R-PE has found more use in flow cytometry and other fluorescence-based applications due to its spike in excitation at 496 nm, which allows for using the 488 nm laser. For this reason, the terms R-PE and PE are often used interchangeably. Our PE-conjugated antibodies are labeled with R-PE.

The main advantages of PE are its exceptional brightness, which can improve the detection of low abundance targets, and its capacity to be excited by the 488 nm laser, found in most fluorescence-based detection systems. PE also has a large Stokes shift, which minimizes self-absorption to reduce unwanted background signal. Other advantages of PE include its high water solubility and resistance to self-quenching. On the flipside, the large size of PE (240 kDa) can preclude its use in applications requiring good penetration into cells and tissues. As such, PE is typically used for detecting cell surface markers. Additionally, because PE is susceptible to photobleaching, it is not recommended for microscopy-based applications.

PE-conjugated antibodies are widely used for multiplex immunoassays. They are especially useful for detecting low abundance targets since the extreme brightness of PE can improve assay sensitivity. When performing multiplex immunoassays that will include PE-based detection, it is important to select fluorophores that are compatible with PE to avoid spectral overlap that could lead to results being misinterpreted.

When using PE-conjugated antibodies in a multiplex immunoassay, it is important to select fluorophores with distinct emission spectra. For example, Alexa Fluor® 647 (emission maximum 665 nm) would be better combined with PE than Alexa Fluor® 488 (emission maximum 525 nm) to minimize spectral overlap. Critically, any fluorophores that are selected should be compatible with the lasers and detectors of the instrument being used.

Tandem dyes consist of two covalently attached fluorophores, a donor and an acceptor. Following laser excitation, the donor emits light, which excites the acceptor via a process called Förster resonance energy transfer (FRET). Because tandem dyes have the excitation properties of the donor and the emission properties of the acceptor, they can increase the number of markers detected per laser. PE is widely used as a donor molecule due to its high extinction coefficient (capacity to absorb energy). PE-tandems are especially useful for multiplex immunoassays, where they allow for measuring more parameters simultaneously.

PE-conjugated antibodies and reagents should be stored at 2-8°C, avoiding exposure to light, and should never be frozen. Freezing can damage the fluorophore, leading to a loss of fluorescence, and may cause PE-conjugated antibodies and reagents to precipitate out of solution.

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Conjugated Antibodies

For the direct detection of your target, explore our offering of over 25 enzyme and fluorochrome conjugated primary antibodies.

Flow Cytometry Reagents

Maximize fluorescence signal intensity and minimize non-specific binding in your flow cytometry assays.

Primary Antibodies

Find a high-quality primary antibody from our fast-shipping selection, all produced to our exacting standards in our own facility.

Secondary Antibodies & Reagents

With a wide range of ready-to-ship secondary antibodies that are second to none, SouthernBiotech will keep your assays running and projects on schedule.