K. Sorimachi, H. Cahnmann
Oct 1, 1977
Citations
0
Influential Citations
24
Citations
Journal
Endocrinology
Abstract
The customary methods for labeling T4 and its analogs, iodination or exchange-labeling, are not applicable to those iodothyronines whose iodine atoms are exclusively in the nonphenolic ring. Therefore, [3,5-125I]diiodo-L-thyronine had to be synthesized by a different method. This synthesis involves the coupling of [125I]diiodo-L-tyrosine with 4-hydroxy-3,5-diiodophenylpyruvic acid to form Lthyroxine labeled in the nonphenolic ring, followed by removal of the two unlabeled iodine atoms in the phenolic ring. High specific activity, limited only by that of the [125I]diiodo-L-tyrosine used as starting material, can be achieved. Radioactivity yields are ∼36% in the coupling reaction and ∼86% in the deiodination reaction, amounting to an overall yield of >30%. L-Thyroxine and 3,5-diiodo-L-thyronine were purified by ion-exchange chromatography. Their radiochemical purity was checked by radiochromatography.