Fmoc-Cys(Trt)-Wang Resin

Fmoc-Cys(Trt)-Wang Resin
Nα-Fmoc-S-trityl-L-cysteine esterified to Wang (4-alkoxybenzyl alcohol) resin; 100–200 mesh, 0.3–0.8 mmol/g

Wang resin preloaded with Fmoc-Cys(Trt)-OH, for making peptide acids with a C-terminal cysteine by Fmoc SPPS. Remove the Fmoc group with 20% piperidine in DMF and build the chain as usual; final cleavage with 95% TFA and scavengers releases the peptide acid and removes the side-chain protecting groups. Include TIS to trap the trityl cation and a thiol such as EDT or DODT to keep the cysteine reduced. The loading for each lot is on its certificate of analysis.

A C-terminal cysteine ester is sensitive to base. During the repeated piperidine treatments it can epimerize, and it can undergo β-elimination to dehydroalanine, which adds piperidine to give a 3-(1-piperidinyl)alanine by-product (+51 Da). Both increase with the number of cycles; for long sequences, 2-chlorotrityl resin keeps them lower.

Applications

• Peptide acids with a C-terminal cysteine for conjugation, labeling or cyclization
• Disulfide-bridged peptides that end in cysteine
• Manual and automated synthesis

Storage
Store refrigerated (2–8 °C) and dry, in a tightly closed container.

References

1. Wang S. p-Alkoxybenzyl Alcohol Resin and p-Alkoxybenzyloxycarbonylhydrazide Resin for Solid Phase Synthesis of Protected Peptide Fragments. Journal of the American Chemical Society 1973, 95, 1328–1333. doi:10.1021/ja00785a602
2. Fujiwara Y et al. Racemization-Free Synthesis of C-Terminal Cysteine-Peptide Using 2-Chlorotrityl Resin. Chemical and Pharmaceutical Bulletin 1994, 42, 724–726. doi:10.1248/cpb.42.724
3. Lukszo J et al. 3-(1-Piperidinyl)alanine formation during the preparation of C-terminal cysteine peptides with the Fmoc/t-Bu strategy. Letters in Peptide Science 1996, 3, 157–166. doi:10.1007/BF00132978

For research use only. Not for human or veterinary use.