Comparison of immunomagnetic beads coated with protein A, protein G, or goat anti-mouse immunoglobulins. Applications in enzyme immunoassays and immunomagnetic separations.
Immunomagnetic beads were prepared using either protein A (PA) or protein G (PG) coupled to magnetic beads for binding antibodies at their Fc region. The performance of these beads was compared with commercially available beads coated with goat anti-mouse (G alpha M) immunoglobulins. Both the PA- and PG-beads possessed a higher binding capacity than the G alpha M-beads for the monoclonal antibodies tested, although, PA bound weakly with some IgG1 antibodies. PA-beads were compared with G alpha M-beads in a magnetic enzyme immunoassay for the detection of mouse immunoglobulins as an alternative to a conventional capture ELISA. The magnetic enzyme immunoassay was characterized by a detection time of less than 60 min and a linear assay range from 5-10 to 500 ng/ml for G alpha M-beads and 5-10 to 1000 ng/ml for PA-beads. The capture ELISA was linear from 10 to 250 ng/ml. For immunomagnetic separation of Salmonella with immunomagnetic beads, PA-beads were superior to both PG- and G alpha M-beads. For specific isolation of bacteria from heterogeneous suspensions by immunomagnetic separation, PA- and PG-beads are preferable since G alpha M-beads crossreact with bacteria possessing proteins with Fc-binding activity.
Widjojoatmodjo
M N
MN
Eijkman Winkler Laboratory for Medical Microbiology, University Hospital Utrecht, Netherlands.
Fluit
A C
AC
Torensma
R
R
Verhoef
J
J
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000911:Antibodies, Monoclonal; D004797:Enzyme-Linked Immunosorbent Assay; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000032:analysis; D007136:Immunoglobulins; D018189:Immunomagnetic Separation; D009419:Nerve Tissue Proteins; D012486:Salmonella typhimurium / Q000276:immunology; D013205:Staphylococcal Protein A
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; C029152:G-substrate; D007074:Immunoglobulin G; D007136:Immunoglobulins; D009419:Nerve Tissue Proteins; D013205:Staphylococcal Protein A