SASRIN (Super Acid Sensitive ResIN) (2-methoxy-4-alkoxybenzyl-alcohol resin)
HO CH2
O CH2
P
CH3O
Peptide is cleavable with 0.5-1.0% TFA in DCM resulted in protected peptide fragments.
✓ Piperidine/DMF (1:4, V/V) is added to the mark;
✓ The mixture is shaken thoroughly and left for 25-30 min;
✓ The resin is filtered off and the absorbance of the filtrate is measured at 301 nm (e = 7800).
The final cleavage results in peptides with COOH group at the C-terminus
The resin is not available for the synthesis of peptides with a sequence on the C-terminal that is sensitive for diketopiperazine formation !
HO CH2 CH3O
O (CH2)3 COOH Attach to aminomethyl PS-DVB resin
Removal of the peptide with diluted TFA
2-Chlorotrityl chloride (Clment of the first amino acid:
peptides (available for fragment condensation).
ClTrt resin prevents the diketopiperazine formation ! Attachment of Cys and His derivatives to the resin is free from
Cl Cl
The final cleavage results in peptides with COOH group at the C-terminus
Cleavage with 90-95% TFA + scavangers results in free peptides Cleavage with AcOH:MeOH(TFE):DCM (1:1:8 or 2:2:6) results in protected
There are many different resins and most of them are used for special cases and in individual laboratories. Here only the most widely applied resins will be presented. Resins are based on PS-DVB (1%) copolymer.
多肽合成工艺流程
2020/8/11
Outline
✓ Resins; ✓ Protecting groups; ✓ Synthetic protocol; ✓ Monitoring; ✓ Cleavage technics; ✓ Side reactions;
Fmoc/tBu:
Fmoc
tert-butyl
4-Alkoxybenzyl alcohol (Wang) resin:
HO CH2
O CH2
P
Attachment of the first amino acid: Fmoc-Aaa(X)-OH:DIC:DMAP (2:2:0.2 equiv to the resin OH content) in DMF, 1h at RT.
1 g ClTrt-resin + 2 mmol Fmoc-Aaa(X)-OH + 8 mmol DIEA in 3-5 mL DCM, for 1.5 h then 0.8 mL MeOH to block the unreacted groups washing with DCM, iPrOH, MeOH, ether
H3C
H3C H3C C CH3
O
TFA
H3C C CH3
R
O
C
CO
C H
..
NH
piperidine
O
H2C
H2C
CH2 O C NH CH C NH CH C O CH2
O
O
O CH2
Wang-resin
Fmoc-Asp(OtBu)-Tyr(tBu)-Wang resin
Type of resins for Fmoc-chemistry
NH2(mmol/g) = [A301.V(ml)/e301.m(mg)].106
2. ca. 4-6 mg Fmoc-Aaa-resin +400 mL 50% piperidine/DMF 30 min at RT, then filtration dilute with MeOH to 25 mL
enantiomerisation!
Determination of loading
(Calculation of the resin capacity) 1.
✓ 10-20 mg of dried resin are weighted exactly into a 100 mL measuring flask (for a load of ca. 0.5 meq/g 20 mg is sufficient);
4-Hydroxymethylphenoxyacetic acid (HMPA) linker:
HO CH2
O CH2 COOH Attach to aminomethyl PS-DVB resin
Removal of the peptide with TFA
4-(4-Hydroxymethyl-3-methoxyphenoxy)butyric acid (HMPB) linker: