Iodination and the Structure of Human Thyroglobulin*

We have studied human thyroglobulin of extremely low iodine content obtained from a goitrous cretin who had no measurable peroxidase activity in his thyroid gland. Thyroglobulin from these patients is of interest because of the possibility that poorly iodinated thyroglobulin is particularly susceptible to dissociation and proteolysis. In the present study our data indicated that poorly iodinated thyroglobin isolated under conditions inhibiting proteolysis possessed properties similar to normal human thyroglobulin in its secondary, tertiary, and quaternary structures.