Y. Nakamura, I. Chopra, D. Solomon
Nov 1, 1977
Citations
0
Influential Citations
65
Citations
Journal
Journal of nuclear medicine : official publication, Society of Nuclear Medicine
Abstract
In order to obtain radioactive iodothyronines of high specific activity, suitable for use in radioimmunoassays, we have used chloramine-T as the oxidizing agent to attach radioiodine to various iodothyronines including 3-iodo-L-thyronine (3-T/sub 1/), 3'-iodo-L-thyronine (3'-T/sub 1/), 3-5-diiodo-L-thyronine (3,5-T/sub 2/), 3,3'-diiodo-L-thyronine (3,3'-T/sub 2/), 3,5,3'-triiodo-L-thyronine (T/sub 3/) and some of their analogues, e.g., 3,5-diiodothyropropionic acid (3,5-Diprop), and 3,5,3'-triiodothyropropionic acid (Triprop). Radioiodine incorporated into iodothyronines was separated from unreacted radioiodide by column chromatography using LH-20 Sephadex, and the various radioactive iodothyronines produced during iodination were separated by descending paper chromatography using hexane, tertiary amyl alcohol, and ammonia. In the case of each substrate, radioactive products produced were those that would result from the radiolabeling of the 3' and/or 5' position of the iodothyronine molecule; compounds that would be produced from radiolabeling of the inner ring of the iodothyronine molecule were never detected. While exchange labeling of outer-ring iodine atoms did occur, addition of an iodine atom to the outer ring was far more common. Our data suggest that the chloramine-T method is practical and convenient to render any iodothyronine (or its analogue) radioactive in the outer ring; and specific activity of the radioactive product and yield of iodination are particularly high when themore » substrate for iodination has one less iodine atom in the outer ring than the one desired.« less