Biotinylated Protein A, S. aureus, Cowan strain

Biotinylated Protein A (B-2001), isolated from a special strain of S. aureus, is a 41 kDa protein which binds to the Fc portion of most immunoglobulins. This interaction is neither species specific nor isotype specific, as Protein A has been shown to bind IgG from a variety of species. Protein A can also interact with IgA, IgM and subclasses of IgG from different species.

Biotinylated Protein A is useful to detect or localize immunoglobulins on cell surfaces or in tissue sections. Used with the appropriate avidin or streptavidin conjugates, immunoglobulins can be studied with brightfield, fluorescence or electron microscopy. Biotinylated Protein A can also be used to detect positive clones in monoclonal antibody production by an avidin or streptavidin enzyme conjugate.

Biotinylated Protein A is used in many systems as a substitute for a biotinylated second antibody. However, in some applications, Biotinylated Protein A may bind to endogenous immunoglobulin in the tissue producing background. In addition, Biotinylated Protein A may not bind to the species or class of primary antibody being employed. For routine immunohistochemical staining we recommend using biotinylated anti-immunoglobulins.