Details

Autor(en) / Beteiligte

• Roll, Marcel
• Montfort, Marie-France
• Valenta, Lubomir
• Lissitzky, Serge

Titel

Iodoamino acid composition of the thyroglobulin of normal and diseased thyroid glands comparison with in vitro iodinated thyroglobulin

Ist Teil von

• Clinica chimica acta, 1972-06, Vol.39 (1), p.95-108

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

1972

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• The iodoamino acid composition has been determined for 78 thyroglobulin preparations purified from thyroid tissue of normal human subjects or from patients with euthyroid or hypothyroid goiters, with treated or untreated Graves' disease, with Hashimoto's thyroiditis or thyroid carcinoma. The Chromatographie method recently described by Rolland et al. 19 was utilized. The iodoamino acid content of normal and other thyroglobulin preparations is essentially related to the iodine content of the protein in the range 0.02 to 0.5%, and not to the origin of the iodoprotein. One exception is thyroglobulin purified from treated Graves' goiters, whose MIT and T 4 content is relatively higher and lower, respectively, than the average value obtained with other native thyroglobulins. Comparisons between in vivo and in vitro iodinated thyroglobulins show differences in the iodoamino acid contents, especially marked for MIT and T 4. Thyroxine formation is definitively favored when iodination takes place in vivo. For thyroglobulins with an iodine content in the range o to 0.5%, the formation of T 4 residues is favored when iodination is conducted at pH 7.4, as compared to iodination at pH 9.0. These results are discussed in terms of the relation between thyroglobulin conformation and the capability of the protein to be iodinated and to form hormone residues. The “native” structure of the protein appears essential for an optimal synthesis of hormonal residues. From a comparative study of the results obtained by the spectrophotometric method of Edelhoch 25,27 and by the Chromatographie method of iodoamino acid analysis, it is concluded that the latter is more appropriate as an index of the iodoamino acid composition of native thyroglobulin, especially when the iodine content of the protein is low.