M. Surks, S. Weinbach, E. Volpert
Jun 1, 1968
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Journal
Endocrinology
Abstract
Recent reports have indicated that 4-hydroxy-3,5-diiodophenylpyruvic acid (dihppa) may be an important intermediate in the biosynthesis of thyroxine. This intermediate has not, however, been identified conclusively in thyroid tissue. Extracts of rat thyroid glands labeled with iodide-125I in vivo were chromatographed on thin-layer silica gel sheets in 2 solvent systems. Radioautographs of these chromatograms showed radioactivity in the dihppa and other areas. Attempts to purify this compound by elution and rechromatography proved unsuccessful. It was shown by ultraviolet spectroscopy that significant structural alterations occurred during these procedures. The resulting compound was tentatively identified as 4-hydroxy-3,5-diiodophenylacetic acid. In other studies, prelabeled rat thyroids were homogenized in hot glacial acetic acid containing 100 mg unlabeled dihppa and 2 mg Nal. The carrier was recrystallized to constant specific activity. After 5 crystallizations the methyl ester of dihppa was synthesize...