Sorimachi K, Cahnmann H J
Endocrinology. 1977 Oct;101(4):1276-80. doi: 10.1210/endo-101-4-1276.
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 metnod. This synthesis involves the coupling of [125I]diiodo-L-tyrosine with 4-hydroxy-3,5-diiodophenylpyruvic acid to form L-thyroxine 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 approximately 36% in the coupling reaction and approximately 86% in the deiodination reaction, amounting to an overall yield of greater than 30%. L-Thyroxine and 3,5-diiodo-L-thyronine were purified by ion-exchange chromatography. Their radiochemical purity was checked by radiochromatography.
标记甲状腺素（T4）及其类似物的常用方法，即碘化或交换标记，不适用于那些碘原子仅存在于非酚环中的碘甲状腺原氨酸。因此，[3,5-¹²⁵I]二碘-L-甲状腺原氨酸必须通过不同的方法合成。该合成过程包括将[¹²⁵I]二碘-L-酪氨酸与4-羟基-3,5-二碘苯丙酮酸偶联，以形成非酚环标记的L-甲状腺素，随后去除酚环中的两个未标记碘原子。可以实现高比活度，其仅受用作起始原料的[¹²⁵I]二碘-L-酪氨酸的比活度限制。偶联反应中的放射性产率约为36%，脱碘反应中的放射性产率约为86%，总产率大于30%。L-甲状腺素和3,5-二碘-L-甲状腺原氨酸通过离子交换色谱法纯化。它们的放射化学纯度通过放射色谱法检查。
