Resin cleavage: difference between revisions
Diff·revision 4 → 5·08:48, 20 Sep 2024
Difference between revision 4 and revision 5 of Resin cleavage. 3 lines changed; the page grew by 278 bytes.
| Revision 4 — 21:00, 5 Sep 2024 StopperingSteff (talk) add the collapse-temperature point, sourced 2,085 bytes +407 | Revision 5 — 08:48, 20 Sep 2024 RepackRadek (talk) split overlong sentence 2,363 bytes +278 | ||
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| 10 | The removed protecting groups generate reactive carbocations, which will alkylate electron-rich side chains — tryptophan, methionine, cysteine and tyrosine — unless captured. Scavengers are included in the cleavage cocktail for that purpose, and their selection depends on which residues the sequence contains.{{r|behrendt2016}} | 10 | The removed protecting groups generate reactive carbocations, which will alkylate electron-rich side chains — tryptophan, methionine, cysteine and tyrosine — unless captured. Scavengers are included in the cleavage cocktail for that purpose, and their selection depends on which residues the sequence contains.{{r|behrendt2016}} |
| 11 | 11 | ||
| + | 12 | Cleavage is therefore not a neutral release step. It is a chemical operation with its own characteristic impurities, and a substantial part of the difference between a clean and a dirty [[Crude peptide|crude]] is decided here.{{r|usp1503}} | |
| + | 13 | ||
| 12 | == Cocktails and scavengers == | 14 | == Cocktails and scavengers == |
| 13 | A typical cocktail is trifluoroacetic acid with a few per cent each of water, triisopropylsilane and, where cysteine or methionine is present, a thiol scavenger. Water and silane trap the tert-butyl and trityl cations; thiols address the more persistent species.{{r|behrendt2016}} | 15 | A typical cocktail is trifluoroacetic acid with a few per cent each of water, triisopropylsilane and, where cysteine or methionine is present, a thiol scavenger. Water and silane trap the tert-butyl and trityl cations; thiols address the more persistent species.{{r|behrendt2016}} |
| ⋮ | ⋮ | ||
| 25 | [[Category:Peptide synthesis]] | 27 | [[Category:Peptide synthesis]] |
| 26 | [[Category:Purification]] | 28 | [[Category:Purification]] |
| + | 29 | [[Category:Impurities and residues]] | |
| 27 | 30 |