Proteins released from stimulated neutrophils contain very high levels of oxidized methionine

Beck‐Speier, Ingrid; Leuschel, Lieselotte; Luippold, Gerd; Maier, Konrad

doi:10.1016/0014-5793(88)81401-7

Cited by 54 publications

(29 citation statements)

References 16 publications

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“…ChT is an oxidizing agent that preferentially oxidizes methionine to methionine sulfoxide (MetO) but it can also oxidize cysteine. Selective oxidation of methionine to MetO by ChT (< 10 mM) has been demonstrated in different proteins [33][34][35][36][37][38][39][40]. Particularly in other ion channels, ChT does indeed act as a Met-preferring oxidizing agent as demonstrated by using electrophysiology and site-directed mutagenesis [20,23].…”

Section: Discussionmentioning

confidence: 97%

Functional consequences of methionine oxidation of hERG potassium channels

Limberis

Martin

et al. 2007

Biochemical Pharmacology

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Reactive species oxidatively modify numerous proteins including ion channels. Oxidative sensitivity of ion channels is often conferred by amino acids containing sulfur atoms, such as cysteine and methionine. Functional consequences of oxidative modification of methionine in hERG1 (human ether à go-go related gene 1), which encodes cardiac I Kr channels, are unknown. Here we used chloramine-T (ChT), which preferentially oxidizes methionine, to examine the functional consequences of methionine oxidation of hERG channels stably expressed in a human embryonic kidney cell line (HEK 293) and native hERG channels in a human neuroblastoma cell line (SH-SY5Y). ChT (300 µM) significantly decreased whole-cell hERG current in both HEK 293 and SH-SY5Y cells. In HEK 293 cells, the effects of ChT on hERG current were time-and concentration-dependent, and were markedly attenuated in the presence of enzyme methionine sulfoxide reductase A that specifically repairs oxidized methionine. After treatment with ChT, the channel deactivation upon repolarization to −60 or −100 mV was significantly accelerated. The effect of ChT on channel activation kinetics was voltage-dependent; activation slowed during depolarization to +30 mV but accelerated during depolarization to 0 or −10 mV. In contrast, the reversal potential, inactivation kinetics, and voltage-dependence of steady-state inactivation remained unaltered. Our results demonstrate that the redox status of methionine is an important modulator of hERG channel.

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Section: Discussionmentioning

confidence: 97%

Functional consequences of methionine oxidation of hERG potassium channels

Limberis

Martin

et al. 2007

Biochemical Pharmacology

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“…Others have shown that hypochlorous acid reacts with proteins by preferentially oxidising cystyl, methionyl, and tryptophanyl residues, and chlorinating amine groups [15][16][17]. The latter breakdown to form aldehydes and nitriles [18].…”

Section: Discussionmentioning

confidence: 99%

Neutrophils convert tyrosyl residues in albumin to chlorotyrosine

1996

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Hypocldorous acid chlorinates tyrosyl residues in small peptides to produce chlorotyrosine. Detection of chlorotyrosine has the potential to unequivocally identify the contribution hypochlorous acid makes to inflammation. I have developed a selective and sensitive HPLC assay for measuring cidorotyrosine. When albumin was exposed to reagent bypochlorous acid, or that produced by myeloperoxidase and stimulated neutrophils, tyrosyl residues in the protein were converted to chlorotyrosine. About 2% of the hypochlorous acid generated by neutrophils was accounted for by the formation of chlorotyrosine. These results demonstrate that chlorotyrosine will be a useful marker for establishing a role for hypochlorous acid in host defence and inflammation.

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“…Thus, based on the assumption that reagent hypochlorous acid reacts similarly to hypochlorous acid generated inside neutrophils, we conclude that the greater degree of chlorination of neutrophil proteins during phagocytosis cannot be attributed to them being more efficiently chlorinated than bacteria. Previously, it was found that neutrophil components including methionine residues (26) and thiols (27,40) undergo extensive oxidation when the cells are stimulated. In these studies it was inferred that hypochlorous acid was responsible for most of the oxidant measured.…”

Section: Chlorination and Killing Of Bacteria Treated With Reagentmentioning

confidence: 99%

“…Chlorination of Neutrophil Proteins during Phagocytosis of Bacteria-Several studies have revealed that neutrophils are susceptible to their own oxidants (26,27). To ascertain whether hypochlorous acid also reacts with neutrophil components, neutrophil proteins were examined for evidence of chlorination.…”

Section: Chlorination and Killing Of Bacteria Treated With Reagentmentioning

confidence: 99%

Chlorination of Bacterial and Neutrophil Proteins during Phagocytosis and Killing of Staphylococcus aureus

Chapman

Hampton

Senthilmohan

et al. 2002

Journal of Biological Chemistry

176

168

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Myeloperoxidase is proposed to play a central role in bacterial killing by generating hypochlorous acid within neutrophil phagosomes. However, it has yet to be demonstrated that these inflammatory cells target hypochlorous acid against bacteria inside phagosomes. In this investigation, we treated Staphylococcus aureus with varying concentrations of reagent hypochlorous acid and found that even at sublethal doses, it converted some tyrosine residues in their proteins to 3-chlorotyrosine and 3,5-dichlorotyrosine. To determine whether or not ingested bacteria were exposed to hypochlorous acid in neutrophil phagosomes, we labeled their proteins with [ 13 C 6 ]tyrosine and used gas chromatography with mass spectrometry to identify the corresponding chlorinated isotopes after the bacteria had been phagocytosed. Chlorinated tyrosines were detected in bacterial proteins 5 min after phagocytosis and reached levels of approximately 2.5/1000 mol of tyrosine at 60 min. Inhibitor studies revealed that chlorination was dependent on myeloperoxidase. Chlorinated neutrophil proteins were also detected and accounted for 94% of total chlorinated tyrosine residues formed during phagocytosis. We conclude that hypochlorous acid is a major intracellular product of the respiratory burst. Although some reacts with the bacteria, most reacts with neutrophil components.Since Metchnikoff (1) first observed phagocytosis of bacteria in white blood cells, numerous investigations have been undertaken to determine the mechanisms responsible for bacterial killing. It is now well established that neutrophils use oxidative and non-oxidative mechanisms to kill bacteria (2, 3). However, our understanding of the precise ways in which these host defenses work is still in its infancy. This is especially true for how neutrophils use oxygen to fight infection. When they phagocytose bacteria, neutrophils rapidly consume oxygen, which is reduced to superoxide by an NADPH oxidase. Superoxide is not toxic to bacteria but spawns numerous other reactive oxygen species that have been implicated in bacterial killing (4). Chief among these is hypochlorous acid, which is formed from hydrogen peroxide and chloride in a reaction catalyzed by myeloperoxidase (5).Results from several studies indicate that myeloperoxidase is required for the majority of oxygen-dependent killing of certain bacteria such as Staphylococcus aureus (4, 6, 7). It is released into phagosomes along with superoxide and hydrogen peroxide (8). However, myeloperoxidase is a complex enzyme with several different activities (5), and it can not be assumed that its predominant function within neutrophil phagosomes is to produce hypochlorous acid. Early studies showing incorporation of chlorine-36 (9) and iodination of bacterial and neutrophil proteins (10) indicated that hypohalous acids are produced when neutrophils undergo phagocytosis. More recently, it was demonstrated that free tyrosine enclosed inside red blood cell ghosts was chlorinated when these vesicles were phagocytosed by neutrophils (11)....

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Proteins released from stimulated neutrophils contain very high levels of oxidized methionine

Cited by 54 publications

References 16 publications

Functional consequences of methionine oxidation of hERG potassium channels

Functional consequences of methionine oxidation of hERG potassium channels

Neutrophils convert tyrosyl residues in albumin to chlorotyrosine

Chlorination of Bacterial and Neutrophil Proteins during Phagocytosis and Killing of Staphylococcus aureus

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