An Iodometric Determination of Methionine

Lavine, Theodore F.

doi:10.1016/s0021-9258(18)72138-8

Cited by 61 publications

(10 citation statements)

References 13 publications

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“…Molecular iodine stoichiometrically converts methionine to dehydromethionine, which has a molecular mass 2 mass units lower than that of methionine . Two diastereomers of dehydromethione are formed in this reaction , .…”

Section: Resultsmentioning

confidence: 99%

“…The oxidation of methionine by iodine is an equilibrium reaction (reaction 1) . Under acidic conditions and in the presence of excess iodide, dehydromethionine oxidizes iodide to triiodide and reverts to methionine. methionine + normalI 3 − ⇄ dehydromethionine + 3 normalI − + normalH + We used the reversibility of the reaction to measure the yield of dehydromethionine produced by hypochlorous acid.…”

Section: Resultsmentioning

confidence: 99%

“…The demonstration that iodine and several N-halo reagents promote formation of dehydromethionine and other azasulfonium cations suggests that reactive halogen species of biological relevance may also generate this product. These include hypochlorous acid and hypobromous acid and the chloramines and bromamines that are derived from them , .…”

mentioning

confidence: 99%

“…Methionine sulfoxide is not the sole two-electron oxidation product of methionine. More than 60 years ago, Lavine demonstrated that iodine oxidizes methionine to dehydromethionine (S-methylisothiazolidine-3-carboxylate) (5). This species is a cyclic product in which the sulfur is bonded to the amine group to form an azasulfonium cation (Figure 1).…”

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Oxidation of Methionine to Dehydromethionine by Reactive Halogen Species Generated by Neutrophils

et al. 2009

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During infection and inflammation, neutrophils and eosinophils produce hypochlorous acid, hypobromous acid, chloramines, and bromamines. These reactive halogen species preferentially oxidize methionine and thiols. It is commonly assumed that they convert methionine to methionine sulfoxide. However, iodine and organic chloramines are known to convert methionine to dehydromethionine, which is a cyclic azasulfonium salt. The potential for this reaction to occur in biologically relevant situations has so far been neglected. Therefore, we investigated the oxidation of methionine and N-terminal methionine residues by biologically relevant reactive halogen species and neutrophils. When hypochlorous acid reacted with methionine, two major products in addition to methionine sulfoxide were formed. They both had molecular masses two mass units lower than that of methionine and were identified as the diastereomers of dehydromethionine. Hypochlorous acid and chloramines converted methionine to a mixture of approximately 25% dehydromethionine and 75% methionine sulfoxide. Hypobromous acid and bromamines produced upward of 50% dehydromethionine. When methionine was present on the N-termini of peptides, reactive halogen species oxidized them to dehydromethionine with yields as high as 80%. Formylated N-terminal methionines and non-N-terminal methionine residues gave stoichiometric production of the corresponding sulfoxides only. Purified myeloperoxidase used hydrogen peroxide and chloride to catalyze the oxidation of N-terminal methionines to dehydromethionine. Neutrophils oxidized extracellular methionine to 30% dehydromethionine and 70% methionine sulfoxide. They also oxidized their intracellular methionine to dehydromethionine as well as methionine sulfoxide. We propose that reactive halogen species will produce dehydromethionine and form azasulfonium cations on the N-termini of peptides and proteins during inflammatory events.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Oxidation of Methionine to Dehydromethionine by Reactive Halogen Species Generated by Neutrophils

et al. 2009

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“…We have therefore reexamined the properties of methionine sulfoximine phosphate, especially data on the infrared spectrum of this and related compounds. Study of the infrared spectra of several derivatives of methionine and dimethyl sulfide indicates that the characteristic absorption bands of the sulfoximine moiety are the N-H stretching frequency at 3200-3350 cm-1 and the bands at 1190-1230 and 1010-3 A similar cyclic compound ("dehydromethionine") was proposed as an intermediate in the reaction of methionine with L, which has been used for the quantitative iodometric determination of methionine (Lavine, 1943;Bakay and Toennies, 1951). A method of preparation and isolation of this compound was briefly described by Lavine (1945).…”

Section: Discussionmentioning

confidence: 99%