Iodination by thyroid peroxidase

Neary, Joseph T.; Soodak, Morris; Maloof, Farahe

doi:10.1016/0076-6879(84)07031-2

Cited by 24 publications

(3 citation statements)

References 90 publications

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“…Therefore, brominated SAPs may be generated by bromination of non-brominated SAPs. Since iodination of tyrosine residues in thyroglobulin is catalyzed by thyroid peroxidase (Neary et al, 1984), the bromination of a phenylalanine residue in SAPs may be carried out by a bromoperoxidase, which has not been isolated from sea urchins but has been isolated from some species of marine algae (Manthey et al, 1984;Wever et al, 1985;Krenn et al, 1989). Most of the halogenated amino acids found in proteins are components of skeletal materials of marine invertebrates (Hunt, 1984).…”

Section: Discussionmentioning

confidence: 99%

Identification of a novel amino acid, o-bromo-L-phenylalanine, in egg-associated peptides that activate spermatozoa

Yoshino¹,

Takao²,

Suhara³

et al. 1991

Biochemistry

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Eight sperm-activating peptides containing a novel amino acid were isolated from the egg jelly of the sea urchin Tripneustes gratilla. Accurate mass measurement of the peptide in FAB mass spectrometry showed that the mass of the novel amino acid residue was 224.978. On the basis of the isotopic ion distribution and the degree of unsaturation, the mass value indicated that the elemental composition of the amino acid residue was C9H801N1Br1, suggesting that the novel amino acid was bromophenylalanine. Proton NMR spectroscopy, amino acid analysis, and RP-HPLC with three synthetic isomers of bromophenylalanine demonstrated that o-bromophenylalanine was the novel amino acid. Derivatization of the amino acid with Marfey's reagent, (1 -fluoro-2,4-dinitrophen-5-yl)-L-alanine amide (FDAA), further indicated that the amino acid was the L-isomer. In other sperm-activating peptides isolated from the egg jelly of the sea urchin, both m-and p-bromophenylalanines were discovered. The presence of m-bromophenylalanine has not been previously reported in natural products, while p-bromophenylalanine is found in theonellamide F, an antifungal bicyclic peptide from a marine sponge.e egg-conditioned media (egg jelly) of sea urchins contain sperm-activating peptides (SAPs)1 that have several effects on sea urchin spermatozoa. They cause stimulation of sperm respiration through intracellular alkalinization (

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Section: Discussionmentioning

confidence: 99%

Identification of a novel amino acid, o-bromo-L-phenylalanine, in egg-associated peptides that activate spermatozoa

Yoshino¹,

Takao²,

Suhara³

et al. 1991

Biochemistry

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“…Iodide (I⁻) is an essential dietary mineral and plays a critical role in thyroid function and development [1]. This anion is concentrated in this gland via the actions of the Na + /I⁻ symporter, where it is used by a specialized heme peroxidase, thyroid peroxidase (TPO) together with hydrogen peroxide (H 2 O 2 ) to generate reactive iodine species (variously reported as atomic iodine I.; iodinium ions, I + ; or hypoiodous acid, HOI) that react with thyroglobulin at specific tyrosine (Tyr) residues [2, 3]. Subsequent processing of the iodinated species gives the thyroid hormones, thyroxine (T4, which contains 4 iodine atoms) and triiodothyronine (T3, the major metabolically active species) [2].…”

Section: Introductionmentioning

confidence: 99%

“…Whilst TPO shows a high specificity for oxidation of I⁻ [3], it can also oxidize other species to a limited extent, with this including the pseudohalide anion, thiocyanate (SCN⁻) [4]. This propensity for oxidation of multiple anions is shared by other members of the peroxidase superfamily, including lactoperoxidase (LPO), eosinophil peroxidase and myeloperoxidase (MPO) [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Elevated levels of iodide promote peroxidase-mediated protein iodination and inhibit protein chlorination

Jokumsen,

Huhle,

Hägglund

et al. 2024

Preprint

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At inflammatory sites, immune cells generate oxidants including H₂O₂. Myeloperoxidase (MPO), released by activated leukocytes employs H₂O₂ and halide/pseudohalides to form hypohalous acids that mediate pathogen killing. Hypochlorous acid (HOCl) is a major species formed. Excessive or misplaced HOCl formation damages host tissues with this linked to multiple inflammatory diseases. Previously (Redox Biology, 2020, 28, 101331) we reported that iodide (I⁻) modulates MPO-mediated protein damage by decreasing HOCl generation with concomitant hypoiodous acid (HOI) formation. HOI may however impact on protein structure, so in this study we examined whether and how HOI, from peroxidase/H₂O₂/I⁻ systems+Cl⁻, modifies proteins. Experiments employed MPO and lactoperoxidase (LPO) and multiple proteins (serum albumins, anastellin), with both chemical (intact protein and peptide mass mapping, LC-MS) and structural (SDS-PAGE) changes assessed. LC-MS analyses revealed dose-dependent iodination of anastellin and albumins by LPO/H2O2with increasing I⁻. Incubation of BSA with MPO/H2O2/Cl⁻ revealed modest chlorination (Tyr286, Tyr475, ∼4%) and Met modification. Lower levels of these species, and extensive iodination at specific Tyr and His residues (>20% modification with>10 µM I⁻) were detected with increasing I⁻. Anastellin dimerization was inhibited by increasing I⁻, but less marked changes were observed with albumins. These data confirm that I⁻ competes with Cl⁻ for MPO and is an efficient HOCl scavenger. These processes decrease protein chlorination and oxidation, but result in extensive iodination. This is consistent with published data on the presence of iodinated Tyr on neutrophil proteins. The biological implications of protein iodination relative to chlorination require further clarification.

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Biochemistry of halogenated organic compounds

Kirk¹

2009

Patai's Chemistry of Functional Groups

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Introduction Biohalogenation Biochemistry of the Thyroid Hormones Biochemistry of Selected Halogenated Organic Compounds Biochemistry of Polyhalogenated Organic Molecules Metabolism of Halogenated Organic Compounds—Biodehalogenation

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Iodination by thyroid peroxidase

Cited by 24 publications

References 90 publications

Identification of a novel amino acid, o-bromo-L-phenylalanine, in egg-associated peptides that activate spermatozoa

Identification of a novel amino acid, o-bromo-L-phenylalanine, in egg-associated peptides that activate spermatozoa

Elevated levels of iodide promote peroxidase-mediated protein iodination and inhibit protein chlorination

Biochemistry of halogenated organic compounds

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