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Fab fragment antibodies are generated by papain digestion of whole IgG antibodies to remove the entire Fc portion, including the hinge region. These antibodies are monovalent, containing only a single antigen binding site. The molecular weight of Fab fragments is about 50 kDa.
Storage and Rehydration: Store freeze-dried solid at 2-8°C. Rehydrate with the indicated volume of dH2O 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 sequential labeling applications.
To complex with primary antibody in solution, use 1:1 weight ratio of Fab:primary antibody (3:1 molar ratio). Vortex and incubate for 30 minutes at room temperature prior to use. Titrate complex to optimal dilution for assay.
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.
RRX (Rhodamine Red-X) conjugates have a peak of excitation at 570 nm and a peak of emission at 590 nm. Although TRITC has been used traditionally with FITC for double labeling, better color separation is achieved by using RRX or Alexa Fluor® 594. Rhodamine Red-X is particularly useful for 3- and 4-color labeling with DyLight 405, Alexa Fluor® 488, and Alexa Fluor® 647 by using a confocal microscope equipped with a 405 nm laser and a krypton/argon laser. Fluorescence from RRX lies about midway between that of Alexa Fluor® 488 and Alexa Fluor® 647, and it shows little overlap with either dye. The krypton-argon laser emits lines at 488 nm, 568 nm, and 647 nm, which are optimal for exciting Alexa Fluor® 488, RRX, and Alexa Fluor® 647, respectively. By adding a 405 nm laser and a 420 nm emission filter, 4-color labeling is possible using DyLight 405-conjugated secondary antibodies from JIR (Figure 5). The separation between all four dyes is perfect for 4-color labeling, and all four dyes are very bright.
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.
Rhodamine Red-X is a trademark of Molecular Probes, Inc. Jackson ImmunoResearch is licensed by Molecular Probes, Inc. to manufacture and sell conjugates of Rhodamine Red-X reactive dye.