Deamidation: difference between revisions
Diff·revision 7 → 8·23:52, 3 Jan 2025
Difference between revision 7 and revision 8 of Deamidation. 5 lines changed; the page grew by 602 bytes.
| Revision 7 — 06:26, 21 Dec 2024 Areapercent_Ayo (talk) add the cross-link to the compendial chapter 2,895 bytes +550 | Revision 8 — 23:52, 3 Jan 2025 StubSorterBot (talk) bot: sort category members 3,497 bytes +602 | ||
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| 20 | Rate rises with pH above about 6, with temperature, and with the flexibility of the local backbone. The Asn-Gly context is the fastest by a wide margin; Asn-Ser and Asn-His are also comparatively fast. Glutamine deamidates by the same mechanism but far more slowly, because the corresponding intermediate is a six-membered ring.{{r|manning2010}} | 20 | Rate rises with pH above about 6, with temperature, and with the flexibility of the local backbone. The Asn-Gly context is the fastest by a wide margin; Asn-Ser and Asn-His are also comparatively fast. Glutamine deamidates by the same mechanism but far more slowly, because the corresponding intermediate is a six-membered ring.{{r|manning2010}} |
| 21 | 21 | ||
| + | 22 | == Detection == | |
| + | 23 | Chromatographically, deamidated species usually elute slightly earlier than the parent on [[Reverse-phase HPLC|reverse phase]] and are better resolved by ion-exchange, which separates on the charge difference that deamidation creates.{{r|usp1503}} | |
| + | 24 | ||
| + | 25 | By mass spectrometry, the +0.984 Da shift requires high-resolution instrumentation to see on a peptide of a few kilodaltons. On a quadrupole instrument a deamidated peptide is indistinguishable from its parent, and a certificate reporting "observed mass matches calculated" from such an instrument has not excluded it.{{r|manning2010}} | |
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| 22 | == References == | 27 | == References == |
| 23 | {{reflist}} | 28 | {{reflist}} |