Proteins indirect iodination

Serum total T4 concentrations were initially determined indirectly, using methods that measured the amount of iodine in a protein precipitate of serum (protein-bound iodine, PBI). In addition to hormonal iodine, the PBI tests also measured iodoproteins, iodotyrosines, inorganic iodine, and thyroglobulin. More specific T4 procedures involved the measurement of hormonal iodine in either a butanol extract of a serum protein precipitate (butanol-extractable iodine) or in a purified fraction of serum (I4 by column). These methods were useful because the iodine in T4 normally accounts for 80% to 90% of all iodine in serum. Both... 

Iodized molecules with low MW serve as ligands in binding assays, for the indirect iodination of proteins, or as photoaffinity ligands. Typically these are phenol compounds. 

Burke (1970) found that fluorine inhibited the sodium-potassium pump and resulted in dysfunction of the iodine pump indirectly, as well as low iodine uptake, thus decreasing serum thyroid hormone levels. KendaU-Taylor (1972) proved that fluorine decreased the production of 3 —5 -cyclic adenosine monophosphate by inhibiting adenylcyclase in the thyroid fluorine also blocked stimulation by TSH. It was also reported that fluorine eliminated 1 from the thyroid in the form of iodized protein. Few studies were reported on synergistic action of iodine and fluorine. 

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