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F(ab')2 fragment antibodies are generated by pepsin digestion of whole IgG antibodies to remove most of the Fc region while leaving some of the hinge region. F(ab')2 fragments have two antigen-binding Fab portions linked together by disulfide bonds and therefore they are divalent. The average molecular weight is about 110 kDa. They are used for specific applications, such as to avoid binding of secondary antibodies to live cells with Fc receptors or to Protein A or Protein G.
1:50 - 1:200 for most applications
Dilution factors are presented in the form of a range because the optimal dilution is a function of many factors, such as antigen density, permeability, etc. The actual dilution used must be determined empirically.
Allophycocyanin (APC) is among several kinds of light-harvesting phycobiliproteins found in red, blue-green, and cryptomonad algae. APC is isolated from the blue-green alga Spirulina, and is chemically cross-linked for stability. After phycobiliproteins are conjugated to secondary antibodies, there is little fluorescence quenching, which results in conjugates of high specific fluorescence compared with conventional fluorophore-antibody conjugates. APC can be excited by light over a wide range of the visible spectrum, is highly water soluble, has a relatively low isoelectric point, and lacks potentially sticky carbohydrates.
It should be noted that the relatively high molecular weight of APC may preclude its use in procedures requiring good penetration into cells and tissues. It is predominantly intended for surface labeling of cells for flow cytometry.
This product is for IN VITRO RESEARCH USE ONLY. It is not a medical device and it is not intended for diagnostic or therapeutic purposes.