Enzyme immunoassay for 11-ketotestosterone using acetylcholinesterase as laberl: application to the measurement of 11-ketotestosterone in plasma of Siberian sturgeon

Abstract A competitive enzyme immunoassay using 11-ketotestosterone (11-KT) covalently coupled to acetylcholinesterase (AChE) from electric eel is developed. Ninety-six well microtiter plates are coated with pure mouse-anti-rabbit-IgG monoclonal antibody and competition is performed in one-step reaction by adding successively 11-KT standard or samples, enzymatic tracer and 11-KT-specific antiserum. This assay is more sensitive (detection limit is 7 pg/ml) than radioimmunoassays previously described, and specificity was not modified by the use of enzymatic tracer. This assay can be performed in less than 5 hr. Validation of the EIA was achieved in a fish model, Siberian sturgeon ( Acipenser baeri ), by comparative determinations of 11-KT levels in plasma extracts using EIA and RIA. Application to the measurement of 11-KT in plasma of farmed Siberian sturgeon during the first reproductive cycle is reported.