TSMS-PC-014
Peptide Cleavage and Global Deprotection Study Guide
School of Peptide Chemistry · Peptide Synthesis and Manufacturing Foundations · Advanced
Open full lessonLearning objectives
- Explain the difference between resin cleavage and side-chain deprotection.
- Describe why cleavage cocktails contain scavengers.
- Recognize sequence-specific cleavage risks.
- Explain how cleavage conditions influence the crude impurity profile.
- Understand why post-cleavage handling affects recovery and stability.
Executive summary
After sequence assembly is complete, the peptide must be released from the resin and side-chain protecting groups must be removed.
In many Fmoc-based workflows, strong acid performs both functions during a global cleavage step.
Cleavage generates reactive protecting-group fragments and carbocations. Scavengers are included to capture these species and reduce reattachment or side-chain modification.
The crude product emerging from cleavage contains:
- intended peptide,
- truncated and deletion sequences,
- incompletely deprotected species,
- reagent-derived by-products,
- protecting-group fragments,
- residual cleavage reagents.
In many Fmoc-based workflows, strong acid performs both functions during a global cleavage step.
Cleavage generates reactive protecting-group fragments and carbocations. Scavengers are included to capture these species and reduce reattachment or side-chain modification.
The crude product emerging from cleavage contains:
- intended peptide,
- truncated and deletion sequences,
- incompletely deprotected species,
- reagent-derived by-products,
- protecting-group fragments,
- residual cleavage reagents.
Key takeaways
- Cleavage and global deprotection are related but distinct functions.
- Linker chemistry controls terminal outcome.
- Scavengers reduce reactive-fragment side reactions.
- Insufficient and excessive cleavage both create quality risks.
- Precipitation is isolation, not final purification.
- Crude analysis guides purification strategy.
Self-review questions
- What is the difference between cleavage and deprotection?
- Why are scavengers used?
- How can excessive cleavage time damage a peptide?
- Why does linker chemistry matter?
- Why is precipitation not proof of purity?
Use the full lesson to verify your answers.