Quantification of digoxin by enzyme immunoassay: synthesis of a maleimide derivative of digoxigenin succinate for enzyme coupling.
We synthesized the m-maleimidobenzoyl derivative of digoxigenin-3-0-succinate (through a p-phenylenediamine bridge) as a hapten derivative directed towards coupling to sulfhydryl grouos of beta-galactosidase. Prepared enzyme conjugate had about 97% of the enzyme labeled with the hapten derivative while retaining full enzyme activity. The enzyme immunoassay for digoxin we prepared showed a maximum sensitivity of 30 pg per assay (c.v. = 3%) with minimal cross-reaction with digotoxin (3.8%). Our method for hapten conjugation to beta-galactosidase is highly efficient and is simple and easily replicated.
D003429:Cross Reactions; D004076:Digoxigenin / Q000031:analogs & derivatives / Q000138:chemical synthesis; D004077:Digoxin / Q000097:blood*; D004926:Escherichia coli / Q000201:enzymology; D006241:Haptens; D006801:Humans; D007124:Immunoenzyme Techniques; D013329:Structure-Activity Relationship; D001616:beta-Galactosidase
D006241:Haptens; D004077:Digoxin; C026999:3-maleimidobenzoyl (digoxigenin-3-O-succinamido)aniline; D001616:beta-Galactosidase; D004076:Digoxigenin