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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.
Storage and Rehydration: Store freeze-dried solid at 2-8°C. Rehydrate with the indicated volume of dH2O (see product specification sheet) and centrifuge if not clear. Prepare working dilution on day of use. Product is stable for about 6 weeks at 2-8°C as an undiluted liquid.
Extended Storage after Rehydration: Aliquot and freeze at -70°C or below. Avoid repeated freezing and thawing. Alternatively, add an equal volume of glycerol (ACS grade or better) for a final concentration of 50%, and store at -20°C as a liquid.
Expiration date: one year from date of rehydration. The expiration date may be extended if test results are acceptable for the intended use.
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.
Cy2 conjugates have maximum absorption/excitation at 492 nm and fluoresce with a peak around 510 nm in the green region of the visible spectrum like FITC conjugates (520 nm), but they are more photostable and less sensitive to pH changes than FITC. However, for mounting in aqueous media we recommend Alexa Fluor® 488 as the preferred green-fluorescing dye because it is brighter and more photostable than Cy2, FITC, and DyLight 488. A further disadvantage of using Cy2 with aqueous mounting media is its sensitivity to p-phenylenediamine, an anti-fading agent found in some commercial mounting media, which results in weak and diffused fluorescence after storage of stained slides. The main advantage of Cy2 conjugates is increased fluorescence in plastic mounting media.
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.
Cy is a trademark of GE Healthcare Bio-Sciences Ltd. Jackson ImmunoResearch is licensed by GE Healthcare Bio-Sciences Ltd. to manufacture and sell conjugates of Cy2, Cy3, and Cy5 reactive dyes under US Patent Number 5,268,486, and other patents pending.