Conjugated primary antibodies are an excellent alternative to using a secondary antibody for detection of your target protein. A conjugated primary antibody is created by pre-attaching (conjugating) a tag of your choice (fluorophore, enzyme, or protein), to a primary antibody, allowing for visualization of your target protein without the need to purchase a costly secondary antibody.

Conjugated primary antibodies can easily replace your previous primary/secondary antibody pairs in the following applications*:

Western blot (WB), Immunohistochemistry (IHC), Immunofluorescence (IF), Immunocytochemistry (ICC), Flow Cytometry (FCM), Fluorescence-activated cell sorting (FACS), Enzyme-Linked Immunosorbent Assay (ELISA), Förster Resonance Energy Transfer (FRET)

Most of StressMarq’s primary antibodies are available conjugated.

To order a conjugated antibody online, simply find your desired primary antibody, then choose the conjugate from the “Conjugate” drop-down list in the ordering section on the product’s page and select “Add to Cart”.

Protein and Enzymes:

• HRP (Horseradish peroxidase)
• Biotin

Fluorophores:

Label	Excitation Max.	Emission Max.	Extinction Coefficient	Substitute for:	Emission
ATTO 390	390	479	2.4×104	–
FITC	494	520	7.3×104	Alexa Fluor® 488
ATTO 488	501	523	9.0×104	Alexa Fluor® 488 FITC
R-PE	565	575	2.0×106	TRITC
ATTO 594	601	627	1.2×105	Alexa Fluor® 594 Texas Red®
APC	650	660	7.0×105	Cy®5 Alexa Fluor® 647 Alexa Fluor® 660
PerCP	482	677	1.96 x 106	–

 

Protein and Enzymes

Fluorophores

Fluorophores, also known as fluorochromes or fluorescent dyes, are chemicals that are excited by light at a specific wavelength and then emit light (fluoresce) at another wavelength.

Key features of fluorophores:

Maximum Excitation Wavelength (λ_ex): The peak in the excitation spectra measured in nanometers (nm).

Maximum emission Wavelength (λ_em): The peak in the emission spectra measured in nanometers (nm).

Stokes Shift: The difference in the maximum wavelength peaks between the emission and excitation spectra, measured in nanometers.

Extinction Coefficient (ε_max): The capacity for the fluorophore to absorb light at a specific wavelength. Usually measured at the maximum excitation wavelength with the units M⁻¹cm⁻¹.

Fluorescence Quantum yield (Φ_f): The number of photons emitted per absorbed photon. This number will range between 0 and 1. A high quantum yield is important.

Fluorescence Decay Time (τ_fl): The time interval after which the number of excited fluorophore molecules decreases to 1/e (approx. 37%), usually measured in nanoseconds.

Brightness: The fluorescence output per fluorophore measured in with the units M⁻¹cm⁻¹. Calculated as the product of the extinction coefficient (at the relevant excitation wavelength) and the fluorescence quantum yield divided by 1000.

 

All ATTO fluorescent dyes are characterized by:

• Strong absorption (high extinction coefficient)
• High fluorescence quantum yield
• High photostability

 

ATTO 390
Overview: High fluorescence yield Large Stokes-shift (89 nm) Good photostability Moderately hydrophilic Good solubility in polar solvents Coumarin derivate, uncharged Low molar mass: 343.42 g/mol  ATTO 390 Datasheet		Optical Properties: λex = 390 nm λem = 479 nm εmax = 2.4×104 Φf = 0.90 τfl = 5.0 ns Brightness = 21.6 Laser = 365 or 405 nm
FITC (Fluorescein)
Overview: Excellent fluorescence quantum yield High rate of photobleaching Good solubility in water Broad emission spectrum pH dependent spectra Molecular formula: C20H12O5 Molar mass: 332.3 g/mol FITC Datasheet		Optical Properties: λex = 494 nm λem = 520 nm εmax = 7.3×104 Φf = 0.92 τfl = 5.0 ns Brightness = 67.2 Laser = 488 nm Filter set = FITC
ATTO 488
Overview: High fluorescence yield High photostability Very hydrophilic Excellent solubility in water Very little aggregation New dye with net charge of -1 Molar Mass: 804 g/mol  ATTO 488 Datasheet		Optical Properties: λex = 501 nm λem = 523 nm εmax = 9.0×104 Φf = 0.80 τfl = 4.1 ns Brightness = 72 Laser = 488 nm Filter set = FITC
R-PE (R-Phycoerythrin)
Overview: Broad excitation spectrum High quantum yield Photostable Member of the phycobiliprotein family Isolated from red algae Excellent solubility in water Molecular Weight: 250 kDa R-PE Datasheet		Optical Properties: λex = 565 nm λem = 575 nm εmax = 2.0×106 Φf = 0.84 Brightness = 1.68 x 103 Laser = 488 to 561 nm Filter set = TRITC
ATTO 594
Overview: High fluorescence yield High photostability Very hydrophilic Excellent solubility in water Very little aggregation New dye with net charge of -1 Molar Mass: 1137 g/mol ATTO 594 Datasheet		Optical Properties: λex = 601 nm λem = 627 nm εmax = 1.2×105 Φf = 0.85 τfl = 3.5 ns Brightness = 102 Laser = 594 nm Filter set = Texas Red®
APC (Allophycocyanin)
Overview: High quantum yield Large phycobiliprotein 6 chromophores per molecule Isolated from red algae Molecular Weight: 105 kDa APC Datasheet		Optical Properties: λex = 650 nm λem = 660 nm εmax = 7.0×105 Φf = 0.68 Brightness = 476 Laser = 594 or 633 nm Filter set = Cy®5
PerCP
Overview: Peridinin-Chlorophyll-Protein Complex Small phycobiliprotein Isolated from red algae Large stokes shift (195 nm) Molecular Weight: 35 kDa PerCP Datasheet		Optical Properties: λex = 482 nm λem = 677 nm εmax = 1.96 x 106 Laser = 488 nm

 

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*The applications listed above are a general list indicating which applications conjugated antibodies can be used in. It does not guarantee that any antibody-conjugate combination has been tested for use in the application.

**Excludes lyophilized antibodies. Please see product detail pages for conjugate availability.

Please note: It is possible that the conjugate tag may bind in the paratope of the antibody, thereby limiting binding of the antibody to the antigen. Although this is unlikely, it could affect the ability of the antibody to bind to the antigen in various species and applications. As we cannot control the binding of the conjugate to the antibody, there is no way to confirm or guarantee the location of the antibody tag.

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