Methionine oxidation: difference between revisions
Diff·revision 2 → 3·01:43, 18 Nov 2024
Difference between revision 2 and revision 3 of Methionine oxidation. 5 lines changed; the page grew by 656 bytes.
| Revision 2 — 10:26, 11 Nov 2024 ColumnOvenCoy (talk) rm the claim that the method is stability-indicating without a forced-degradation study 1,416 bytes ±0 | Revision 3 — 01:43, 18 Nov 2024 PuffRemoverPax (talk) add the figure for the chromatogram and caption its axes 2,072 bytes +656 | ||
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| 10 | Oxidation is promoted by dissolved oxygen, by trace transition metals, by peroxide impurities in excipients, and by light. Unlike [[Deamidation|deamidation]], which proceeds spontaneously in clean aqueous solution, oxidation generally requires an oxidant, and controlling the oxidant is therefore an effective control strategy.{{r|usp1503}} | 10 | Oxidation is promoted by dissolved oxygen, by trace transition metals, by peroxide impurities in excipients, and by light. Unlike [[Deamidation|deamidation]], which proceeds spontaneously in clean aqueous solution, oxidation generally requires an oxidant, and controlling the oxidant is therefore an effective control strategy.{{r|usp1503}} |
| 11 | 11 | ||
| + | 12 | == Chemistry and promoters == | |
| + | 13 | The sulfur of methionine is readily oxidised by two-electron oxidants such as hydrogen peroxide to the sulfoxide, a reaction that is fast and essentially irreversible under ordinary conditions. Further oxidation to the sulfone requires more forcing conditions and is less commonly observed in practice.{{r|manning2010}} | |
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| + | 15 | Metal-catalysed oxidation is the more insidious route. Trace iron or copper, in the presence of oxygen and a reducing agent, generates reactive species locally at metal-binding sites, so oxidation can be site-specific rather than uniform. Chelating agents in formulations exist largely to suppress this. | |
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| 12 | == References == | 17 | == References == |
| 13 | {{reflist}} | 18 | {{reflist}} |