Particulate iodoprotein in abnormal thyroid glands.

Abstract

The distribution of stable iodine has been measured in 14 abnormal human thyroid glands, and the distribution of radioiodine has been measured in 6 of these. More than 10% of the stable iodine of 12 specimens from 8 patients was associated with the “nuclear” centrifugal fraction, and this fraction accounted for nearly half the stable iodine and radioiodine of a diffusely hyperplastic congenital goiter with a high total iodine content. When measured, the specific activity of the radioiodine in these glands was usually less in the particulate centrifugal fractions than in the soluble fraction. The iodine of the “nuclear” fraction could be solubilized partially by urea and thioglycolate, and by 15-min exposure to trypsin. The solubilized iodoprotein moved near thyroglobulin by starch gel electrophoresis, differed from thyroglobulin in salting-out characteristics, and contained MIT and DIT but no detectable iodothyronine.