Fluorophotometric enzyme immunoassay of neocarzinostatin using peroxidase as a label.

Abstract

A sensitive enzyme immunoassay for the determination of neocarzinostatin (NCS), a proteinaceous antitumor antibiotic, has been developed. Horseradish peroxidase was used as the labeling enzyme and was conjugated with NCS according to Nakane's method. Separation of bound and free fractions was achieved by a double antibody solid phase method using Sepharose 4B gel coupled with purified IgG of goat anti-rabbit IgG serum. Thyramine and hydrogen peroxide were used as substrates for the fluorophotometric assay of peroxidase activity. A satisfactory standard curve for NCS was obtained in the range of 10 to 1000 pg/assay tube, corresponding to the range of 0.5 to 50 ng/ml of sample solution. This enzyme immunoassay could be applied to the determination of NCS in serum after its administration to rabbits. NCS in various tissue homogenates could also be assayed by this method.