~-14C]Tyrosine-labeled noniodinated hog thyroglobulin was iodinated enzymatically and nonenzymatically (iodine, iodide-chloramine-T, pH 7.4, or iodine monochloride, p.H 8.1). This led to similar levels of iodine incorporatzon as well as of thyroid hormone synthesis. Iodine monochloride at pH 5.5 formed “hormonogenic” iodotyrosine residues, but no hormone residues. The latter were formed when th...