Studies on the Mechanism of the Iodination of Tyrosine by Lactoperoxidase

Huber, R.E.; Edwards, L. A.; Carne, T. J.

doi:10.1016/s0021-9258(18)94198-0

Cited by 27 publications

(10 citation statements)

References 16 publications

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“…In contrast, Tyr-111, although predicted to be located in a hydrophobic environment, was reactive in both cases. In agreement with studies on the mechanism of lactoperoxidase-catalyzed iodination of tyrosine (Huber et al, 1989), this suggests that surface accessibility is not an absolute prerequisite for iodination of tyrosine residues in proteins and that the reactivity of a particular tyrosine residue depends primarily on its ionization and other factors related to its microenvironment.…”

Section: Discussionsupporting

confidence: 84%

Effect of lactoperoxidase-catalyzed iodination on the calcium-dependent interactions of human C.hivin.1s. Location of the iodination sites

Illy¹,

Thielens²,

Gagnon³

et al. 1991

Biochemistry

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C-1s, one of the two serine proteases of C-1, the first component of complement, has the ability to mediate heterologous (C-1r-C-1s) as well as homologous (C-1s-C-1s) Ca(2+)-dependent interactions both involving the NH2-terminal alpha region of its A chain. Lactoperoxidase-catalyzed iodination of C-1s in its monomeric form was found to abolish its ability to form Ca(2+)-dependent homodimers, without impairing its ability to mediate C-1r-C-1s heteroassociation. C-1s iodinated in its dimeric form, in contrast, fully retained the ability to self-associate. With a view to identify the tyrosine residues iodinated in each case, C-1s was radioiodinated in its monomeric and dimeric forms, and comparative tryptic mapping was performed on the resulting 125I-labeled A chains. Most of the tyrosine residues either were not iodinated or were equivalently but not in the dimer. Conversely, Tyr-52 and Tyr-147 were iodinated only in the dimer. These results provide further evidence that the structural determinants of C-1s required for Ca2+ binding and Ca(2+)-dependent protein-protein interactions are contributed by both the NH2-terminal motif I (positions 1-110) and the epidermal growth factor like motif II (positions 111-159) of the alpha region. On the basis of available information, tentative models of the C-1s-C-1s and C-1r-C-1s Ca(2+)-dependent interactions are proposed.

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Section: Discussionsupporting

confidence: 84%

Effect of lactoperoxidase-catalyzed iodination on the calcium-dependent interactions of human C.hivin.1s. Location of the iodination sites

Illy¹,

Thielens²,

Gagnon³

et al. 1991

Biochemistry

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“…Essential to this experimental strategy, when it is applied to studying the topology of anion exchanger, is a reagent that is specific for the functional group of only one particular type of amino acid and that cannot pass through the barrier provided by the plasma membranes of the erythrocytes. Lactoperoxidase, a high molecular weight protein obtained from bovine milk, has often been used to catalyze the iodination of tyrosine residues on anion exchanger (Morisson & Bayse, 1970;Morrison, 1980), even though the exact identity of the iodinating species generated when lactoperoxidase, iodide, and hydrogen peroxide are mixed together is unclear (Morrison & Schonbaum, 1976;Sun & Dunford, 1993;Huwiler et al, 1985;Huber et al, 1989). The conditions that have been established before and those that were used here, however, have been shown in both intact erythrocytes and sealed vesicles prepared from rough microsomes of rat liver to iodinate only the proteins on the exposed, exterior surface of the respective membranes while neither the intracellular hemoglobin nor the soluble components inside the microsomes were significantly labeled (Phillips & Morrison, 1970;Hubbard & Cohn, 1972;Kreibich et al, 1974).…”

Section: Discussionmentioning

confidence: 99%

Topological Disposition of Tyrosine 486 in Anion Exchanger from Human Erythrocytes

Kalo

1996

Biochemistry

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The location with respect to the plasma membrane of tyrosine 486 in the native anion exchanger of human erythrocytes has been determined by site-directed immunochemistry. Intact erythrocytes and inside-out vesicles were [125I]radioiodinated by lactoperoxidase in the same vessel. After the erythrocytes and inside-out vesicles had been separated by differential centrifugation, the modified polypeptide of the anion exchanger was isolated from each sample and digested with the proteinase from Staphylococcus aureus strain V8 and trypsin to generate the peptide YIVGR. An immunoadsorbent that was specific for the carboxy-terminal sequence -IVGR was used to purify the peptide YIVGR, which contains tyrosine 486 of the anion exchanger, from the products of the digestion. The [125I]radioiodinated peptides isolated by the immunoadsorbent were submitted to high-pressure liquid chromatography, and their respective mobilities were compared to those of synthetic peptides that had been iodinated at tyrosine. By applying this technique, the peptide containing tyrosine 486 was unambiguously identified, and the incorporation of [125I]iodine into this residue in anion exchanger could be monitored. When inside-out vesicles and intact cells were [125I]radioiodinated in the same suspension, tyrosine 486 was modified to at least a 6-fold greater specific radioactivity in the inside-out vesicles than it was in the intact cells. This amino acid, therefore, was assigned to the cytoplasmic surface of native anion exchanger. It follows that the polypeptide of anion exchanger spans the membrane three times before it reaches the extracellular region surrounding glutamine 550.

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“…The native LPO enzyme has its absorption maxima at 412, 500, 542, 590 and 630 nm. 35 The spectra of the LPO-H 2 O 2 system follow at a l o 280 nm the order (Fig. 6B, starting from below): native LPO, initial (at time zero [t 0 ] of adding H 2 O 2 ), 5 min, increasing until we reach the final time (40 min).…”

Section: Kinetic Study Of Lpomentioning

confidence: 94%

Inhibition of peroxidase-catalyzed iodination by thioamides: experimental and theoretical study of the antithyroid activity of thioamides

et al. 2011

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Studies on the Mechanism of the Iodination of Tyrosine by Lactoperoxidase

Cited by 27 publications

References 16 publications

Effect of lactoperoxidase-catalyzed iodination on the calcium-dependent interactions of human C.hivin.1s. Location of the iodination sites

Effect of lactoperoxidase-catalyzed iodination on the calcium-dependent interactions of human C.hivin.1s. Location of the iodination sites

Topological Disposition of Tyrosine 486 in Anion Exchanger from Human Erythrocytes

Inhibition of peroxidase-catalyzed iodination by thioamides: experimental and theoretical study of the antithyroid activity of thioamides

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