Quantitation of Thyroid Hormone Binding to Anti-Thyroxine Antibody Fab Fragment by Native Mass Spectrometry

Senthil K. Thangaraj, Henri Arola, Antti Tullila, Tarja K. Nevanen, Juha Rouvinen, Janne Jänis

    Research output: Contribution to journalArticleScientificpeer-review

    Abstract

    Thyroid hormones are important regulatory hormones, acting on nearly every cell in the body. The two main thyroid hormones are l-thyroxine (tetraiodo-l-thyronine, T4) and 3,3′,5-triiodo-l-thyronine (T3), which are produced in the thyroid gland and secreted into the blood stream. Other important thyroid hormone metabolites are 3,3′-diiodo-l-thyronine (T2) and l-thyronine (T0), which may show increased levels in circulation due to dietary iodine deficiency or other medical disorders. Owing to their central role in cellular functions, sensitive and specific detection methods for thyroid hormones are needed. In this work, native mass spectrometry (MS) was used to quantitate thyroid hormone binding to the anti-T4 antibody Fab fragment. First, the binding affinity for T2 was determined via direct ligand titration experiments. Then, the affinities for the other ligands were determined by competition experiments using T2 as the "low-affinity" reference ligand. The highest affinity was measured for T3, followed by T4, T2, and T0 (Kd = 29, 3.4, and 260 nM and 130 μM, respectively). Thus, it is evident that the number and positions of the iodine substituents within the thyronine rings are important for the ligand binding affinity of anti-T4 Fab. Surprisingly, structurally related tetrahalogen bisphenols were also able to bind to anti-T4 Fab with nanomolar affinities.

    Original languageEnglish
    Pages (from-to)18718-18724
    JournalACS Omega
    Volume4
    Issue number20
    DOIs
    Publication statusPublished - 31 Oct 2019
    MoE publication typeA1 Journal article-refereed

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