Crude peptide (revision 3)
Old revision·23:45, 26 Sep 2024·INN_Ingrid
| Crude peptide | |
|---|---|
| Obtained from | Cleavage of the assembled chain |
| Typical purity | Highly variable; sequence-dependent |
| Principal impurities | Deletion and truncated sequences |
| Topic infobox · conventions | |
Crude peptide is the material obtained immediately after cleavage from the solid support, before any chromatographic purification. It contains the target peptide together with every by-product that accumulated during assembly and cleavage.[1]
Its purity is highly variable and is largely determined by sequence. An easy 10-residue sequence may cleave at high purity; a difficult 40-residue sequence may cleave at well under half. That figure sets the cost and difficulty of everything that follows.[1]
What is in it
[edit]The dominant impurities are sequence-related: deletion sequences missing one or more residues where a coupling failed, truncated sequences where a chain was capped, and any peptide bearing residual protecting groups where cleavage was incomplete.[1][2]
Cleavage adds its own. Strongly acidic conditions release reactive cations from the protecting groups, which can alkylate tryptophan, methionine and cysteine unless scavengers capture them; oxidation and, for susceptible sequences, aspartimide formation also occur.
References
- ^ a b c Behrendt R, White P, Offer J. "Advances in Fmoc solid-phase peptide synthesis." Journal of Peptide Science 22(1):4–27 (2016). PMID 26785684.
- ^ Merrifield RB. "Solid phase peptide synthesis. I. The synthesis of a tetrapeptide." Journal of the American Chemical Society 85(14):2149–2154 (1963). DOI:10.1021/ja00897a025.