Heterologous enzyme immunoassay for puromycin aminonucleoside using beta-D-galactosidase as a label.

A heterologous enzyme immunoassay (EIA) was developed to quantify puromycin aminonucleoside (PA). This double antibody assay was based on the use of anti-puromycin (PU) antibody and used beta-D-galactosidase-labeled PA conjugate prepared via N-(m-maleimidobenzoyloxy)succinimide. The standard curve of the assay ranged from 1 ng to 30 ng, and the lower limit of detection was 22.7 nM (1 ng/tube). The EIA was found to be approximately 20 times more sensitive than the homologous EIA for PA with anti-PA antibody and PA-beta-D-galactosidase conjugate. The heterologous EIA was free from interference by any purine or pyrimidine analogs and drug levels were easily determined in rat tissue following i.v. administration at a dose of 15 mg/kg. The sensitivity and specificity of the EIA should provide a valuable new tool for use in pharmacokinetic and toxicity studies of PA.