Procedure for radiolabeling gizzerosine and basis for a radioimmunoassay

A method for the labeling of gizzerosine (GZ), a biogenic amine found in fi sh meal, is described. The labeling procedure with I-125 using a water-solu ble Bolton-Hunter reagent and a mild water-insoluble oxidant (Iodogen) reag ent is rapid and reproducible. The I-125-GZ hapten was demonstrated to be i mmunologically active in a radioimmunoassay developed with polyclonal antib odies to GZ absorbed with a histamine-Sepharose column. The curves were lin ear in the range of 0.0001 and 0.1 mu g/mL. Samples of fish meal previously extracted of histamine with methanol and submitted to acid hydrolysis were contaminated with known amounts of GZ and submitted to the assay. The fish meal samples contaminated with GZ show a dose-response effect similar to t he standard curve, and apparently the other component present in the sample did not interfere with the binding of the antibodies to I-125-GZ. These da ta indicate the suitability of the radioimmunoassay to determine specifical ly GZ in fish meal.