Cleavage
Cleavage refers to the final
removal of the peptide from the resin as well
as selective removal of amino acid side chain
protecting groups. This process is performed
with Trifluoroacetic acid (TFA) and scavengers.
Scavengers are used to surround the amino acid
side chain protecting groups and prevent them
from reattaching to the peptide.
Before performing the cleavage, the resin should be washed with DCM to
remove all traces of DMF. Residual basic DMF can inhibit TFA acidolysis.
Various amino acid side chain protecting groups require different scavengers
to be added to the TFA cleavage mix.
| Peptides |
Cleavage
Mix (v/v) |
1. Any
Peptide
(82.5/5/5/5/2.5) |
TFA/thioanisole/water/phenol/EDT |
| 2. Any
except Arg(Mtr) or unprotected Trp |
TFA/TIS/water/EDT
(94/1/2.5/2.5) |
3. Any
except Arg(Mtr), Cys(Trt),Met,
or unprotected Trp |
TFA/TIS/water
(95/2.5/2.5) |
References
EMD Biosciences Technical
Note, "Fmoc Resin Cleavage and Deprotection" 2001.
http://www.emdbiosciences.com/SharedImages/TechnicalLiterature/6_Fmoccleavage.pdf
|
