title: Conformational change of the thyroglobulin molecule induced by oxidation in vitro.
abstract: Previous electron-microscopical studies from this laboratory have shown that the thyroglobulin molecule can occur in two different conformations, one ovoid and the other cylindrical. Ovoid molecules are characteristic of well-iodinated thyroglobulin whereas cylindrical molecules are found after low-iodine diet or blocking of iodination. The present study was performed in order to elucidate the possible relation between the molecule conformation and the peroxidase-catalyzed reactions that occur in the thyroid in connection with hormone synthesis. Cylindrical thyroglobulin molecules (from PTU-exposed thyroids) were incubated in different media and the proportion of cylindrical and ovoid molecules after incubation was estimated in electron micrographs. It was found that incubation with glucose-glucose oxidase caused an extensive conversion of cylindrical molecules into ovoid molecules. Peroxidase and/or iodide were not necessary for this change of conformation. It is suggested that this in vitro molecule transformation was the result of an oxidation reaction.
mesh_terms: D000818:Animals; D005947:Glucose; D005949:Glucose Oxidase; D006801:Humans; D007454:Iodides; D008854:Microscopy, Electron; D010084:Oxidation-Reduction; D010544:Peroxidases; D011441:Propylthiouracil / Q000494:pharmacology; D011487:Protein Conformation; D051381:Rats; D013954:Thyroglobulin; D013961:Thyroid Gland / Q000032:analysis / Q000187:drug effects
chemical_list: D007454:Iodides; D011441:Propylthiouracil; D013954:Thyroglobulin; D005949:Glucose Oxidase; D010544:Peroxidases; D005947:Glucose