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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 (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.
1:200 - 1:1000 for sequential labeling applications.
To complex with primary antibody in solution, use 1:1 weight ratio of Fab:primary antibody (15:1 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.
Biotin-SP is our trade name for biotin with a 6-atom spacer positioned between biotin and the protein to which it is conjugated. When Biotin-SP-conjugated antibodies are used in enzyme immunoassays, there is an increase in sensitivity compared to biotin-conjugated antibodies without the spacer. This is especially notable when Biotin-SP conjugated antibodies are used with alkaline phosphatase-conjugated streptavidin. Apparently, the long spacer extends the biotin moiety away from the antibody surface, making it more accessible to binding sites on streptavidin. Biotinylated antibodies require an additional reagent for visualization. We offer streptavidin and Mouse Anti-Biotin conjugated to fluorophores and enzymes.
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.