Study of the Hydrolysis of Thyroid Tissue for the Quantitative Recovery of] Iodinated Compounds A method of removing the iodinated compounds frem thyroid tissue as labeled thyroid tissue and other types of tissue. preliminary This was done to test t of the recovery of each iodinated compound under controlled conditions. A]reducing agent was added to the hydrotysis to inhibit interchange of iodine atoms during the precess of hydrolysis. I remained bound to each of the original c the exception that as much as 17% of 151] in thyroxine might be freed as 1 thyroxine was exposed to the hydrolysis of thyroid tissue. The compourd, hydrolysis. Triiodcothyronine sometimes represented as much as 20% of the fotal yield of iodinated compounds from tissue. The methods which were developed were used to quantitatively study synthesis of thyroid hormone in thyroid tissue when 1317 had been given as to rabbits. The work utilizing this method of separation of iodinated was published in 1953. Dobyns, B.M., and Barry, S.R.: The Isclation of Icdinated Amino Acids Tissue by Means of Starch Colum Chromatography? J. Biol. Chem. 204: 417-5 September, 1953. label acids Thyroid This report described the quantitative changes in the i dide and ¢ iodin pred compounds in the id as time sed following a dose of T given to rpbbits. It also Soneieaesa of thepreceding 3 years on the development of the the reproducibility of the results, the identification of the campounds andj their individual stability in the system, and the nature and control of the hydrofysis of thyroid tissue. The biological turnover of iodine was illustrated in rabbi studying the thyroid at various intervals of time after 1311 had heen give attached Figure 2. Although the iodide fraction contained a large amount o and the thyroxine fraction contained very little, the icdide and thyroxine shifted in favor of the thyroxine with the passage of time. The mono- and fiiodo fractions were major sites of 131I in the gland during both the early and lite periods of observation. The prompt observance and thereafter steady state of the ifotope in ‘the mono— and diiodotyrosine fraction prompted the hypothesis that mono- ang > d somewhat more separation of thyroxine and triiodothyronine than did the sta and was therefore used for this purpose in some experiments. A great deal was devoted to resolving the forerunning mixture of unseparated substances. However, this proved fruitless and the method was abandoned.