Is Iodide Required for Peroxidase-Catalyzed Coupling in Thyroglobulin?

  • L. Lamas


There is controversy regarding the possible role of iodide in the coupling reaction. We first reported (1,2) that chemically iodinated thyroglobulin (Tgb), containing almost no iodothyronines and dialyzed to remove the remaining excess of iodide, would give rise to a significant amount of thyroid hormones when incubated in the presence of a peroxidase system (thyroid or lactoperoxidase and glucose, glucose oxidase as H2O2 generating system) in the absence of added iodide, presumably by coupling of the preformed iodotyrosines. It was subsequently reported (3) that chemically iodinated Tgb releases iodide when incubated with peroxidase, suggesting that iodide is needed for coupling to occur and that maximal coupling rates are obtained with an iodide concentration as high as 100 μ M. More recently (4), it has been reported that free iodide is an inhibitor of iodothyronine synthesis in vitro and that, in the presence of limiting H2O2, it actively regulates the efficiency of coupling.


Coupling Reaction Glucose Oxidase Paper Chromatography Multinodular Goiter Iodide Concentration 
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    Lamas L, Santisteban P, and Turmo C. Annales d’endocrinologie 45: 125A, 1984.Google Scholar
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    Lamas L. Eur J Biochem 96: 93, 1979.PubMedCrossRefGoogle Scholar
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    Nunez J. In F Wold and K Moldave (eds), Methods of Enzymology vol. 107, Academic Press, Inc., 1984, p 476.Google Scholar

Copyright information

© Springer Science+Business Media New York 1986

Authors and Affiliations

  • L. Lamas
    • 1
  1. 1.Departamento de Endocrinologia Experimental, Instituto de Investigaciones BiomedicasFacultad de Medicina, C.S.I.C.MadridSpain

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