Preparation of high-quality iodine-125-labelled pituitary human follicle-stimulating hormone (hFSH) for radioimmunoassay: comparison of enzymatic and chloramine-T iodination.

A method is described for the enzymatic radioiodination of human follicle-stimulating hormone (hFSH) by a system consisting of lactoperoxidase, hydrogen peroxide and Na125I. It was compared with the Chloramine-T modified technique. A satisfactory specific activity of the labelled hormone was obtained with the enzymatic iodination with much greater immunoreactivity was stability than after Chloramine-T.