title: High-level conjugation of chelating agents onto immunoglobulins: use of an intermediary poly(L-lysine)-diethylenetriaminepentaacetic acid carrier.
abstract: Diethylenetriaminepentaacetic acid (DTPA), a strong chelating agent, was covalently linked to murine monoclonal anti-HLA IgG1 antibody (H-1) with the use of poly(L-lysine) (Mr 14,000) as a multivalent, intermediary carrier, via thiol-disulfide exchange reaction. The conjugates contained up to 42.5 mol DTPA per mol antibody, and retained over 90% of their antibody activity in vitro. The conjugates incorporated gadolinium (Gd) through an exchange reaction with Gd-EDTA, used to prevent colloid formation and nonspecific binding of the free metal. The IgG-poly(L-lysine)-DTPA-Gd had a greater effect per mol on proton relaxation rates than DTPA-Gd itself. Use of poly(L-lysine) as an intermediary carrier for attachment of chelating agents to IgG thus offers great potential for achieving high-specific-activity conjugates, particularly for use as biologically specific contrast agents in nuclear magnetic resonance imaging.
mesh_terms: D000911:Antibodies, Monoclonal; D002460:Cell Line; D004220:Disulfides; D004591:Electrophoresis, Polyacrylamide Gel; D005682:Gadolinium; D006801:Humans; D007074:Immunoglobulin G; D009682:Magnetic Resonance Spectroscopy; D004369:Pentetic Acid; D011107:Polylysine; D013388:Succinimides; D013438:Sulfhydryl Compounds
chemical_list: D000911:Antibodies, Monoclonal; D004220:Disulfides; D007074:Immunoglobulin G; D013388:Succinimides; D013438:Sulfhydryl Compounds; D011107:Polylysine; C018151:N-succinimidyl 3-(2-pyridyldithio)propionate; D004369:Pentetic Acid; D005682:Gadolinium