what is thyroxine in biology
thyroxine, thyroxin. a hormone of the thyroid gland that contains iodine and is a derivative of the amino acid tyrosine. The chemical name for thyroxine is tetraiodothyronine (symbol, T 4); it is formed and stored in the thyroid follicles as thyroglobulin, the storage form. hormone of the thyroid gland that contains iodine and is a derivative of the amino acid tyrosine. The chemical name for thyroxine is tetraiodothyronine (symbol, T 4); it is formed and stored in the thyroid follicles as thyroglobulin, the storage form.