NorthernLights™ fluorescent secondary antibodies and streptavidin conjugates are bright and resistant to photobleaching. We are currently offering secondary antibodies recognizing mouse, rat, goat, sheep, and rabbit IgG as well as chicken IgY. These reagents are available with three distinct excitation and emission maxima, making them ideal for multi-color fluorescence microscopy (Figure 1). Their spectral properties are similar to several frequently used fluorochromes and can be used with common filter sets and/or lasers (see the table below).
- Photostable: Resistant to photobleaching
- Comparable spectral properties to many common fluorochromes limiting the need for additional instrumentation
- Specific antibodies deliver low background and high signal-to-noise ratio
- Stable in alcohols and xylene
- Suitable for fluorescence microscopy and flow cytometry
Streptavidin, a protein of 55,000 Daltons, can bind 4 moles of biotin per mole of protein. The complex formed between streptavidin-biotin is stable over a wide range of pH and temperatures. Streptavidin lacks carbohydrate residues present in the avidin molecule reducing non-specific interactions with surface molecules. The dissociation constant for biotin is approximately 10-15 M. Streptavidin conjugated NorthernLights Fluorochromes are an excellent choice for visualization of proteins detected using biotinylated antibodies.
|NorthernLights Secondary Reagents
||Fluorochromes with Comparable Spectrums (Abs/Em)
|NL-493 anti-Sheep IgG
Alexa Fluor® 488 (494/519)
|NL-493 anti-Rabbit IgG
|NL-493 anti-Mouse IgG
|NL-493 anti-Rat IgG
|NL-493 anti-Goat IgG
|NL-493 anti-Chicken IgY
|NL-557 anti-Sheep IgG
Rhodamine Red™ X (570/590)
|NL-557 anti-Rabbit IgG
|NL-557 anti-Mouse IgG
|NL-557 anti-Rat IgG
|NL-557 anti-Goat IgG
|NL-557 anti-Chicken IgY
|NL-637 anti-Sheep IgG
Alexa Fluor® 647 (650-668)
|NL-637 anti-Rabbit IgG
|NL-637 anti-Mouse IgG
|NL-637 anti-Rat IgG
|NL-637 anti-Goat IgG
|NL-637 anti-Chicken IgY
||Figure 1. Rat cortical stem cell differentiation was monitored using multi-color immunocytochemistry. Neural progenitors were labeled with R&D Systems goat anti-rat nestin polyclonal antibody (Catalog # AF2736) and stained with R&D Systems donkey anti-goat NorthernLights-493 secondary antibody (Catalog # NL003; green). Differentiated neurons were labeled with R&D Systems neuron-specific mouse anti-beta-III tubulin monoclonal antibody (TuJ-1; Catalog # MAB1195) and stained using R&D Systems donkey anti-mouse NorthernLights-557 secondary antibody (Catalog # NL007; red). Nuclei were stained with DAPI (blue).
Alexa Fluor is a registered trademark of Invitrogen.
Rhodamine Red is a trademark of Invitrogen.
Cy is a trademark of GE Healthcare.