Ramage Amide AM Resin: Fmoc-Compatible Resin for C-Terminal Peptide Amides
Ramage Amide AM Resin is a Fmoc-compatible polystyrene resin functionalized with the Ramage linker, a derivative of 4-(hydroxymethyl)-3-methoxyphenoxyacetic acid (HMPA), attached to an aminomethylated polystyrene (AM) support. This resin is specifically designed for the solid-phase synthesis of peptide amides, producing a C-terminal –CONH₂ group upon acidic cleavage.
Named after the chemist Dr. Robert Ramage, this linker offers greater acid lability than the standard Rink amide resin, enabling milder cleavage conditions while maintaining compatibility with standard Fmoc/tBu strategies.
Specifications
Matrix: Polystyrene cross-linked with ~1% DVB
Linker: Ramage (HMPA-based) amide linker
Base Resin: Aminomethylated polystyrene (AM resin)
Functional Group: Amide linker (cleaves to give C-terminal amide)
Loading: Typically 0.4–0.8 mmol/g
Particle Size: 100–200 mesh (75–150 µm)
Compatible Chemistry: Fmoc/tBu peptide synthesis
Cleavage Conditions: Acidic (TFA), typically milder than for Rink Amide resin
Key Features
C-Terminal Amides: Produces biologically relevant amide-terminated peptides
Milder Cleavage Conditions: Cleaves more readily than Rink Amide resin
Fmoc-Compatible: Works with all standard SPPS workflows
High-Purity Crude Peptides: Clean linker chemistry with minimal by-products
Robust Stability During Synthesis: Compatible with repetitive base and coupling steps
Applications
Synthesis of peptide amides for pharmaceutical and biological studies
Bioactive peptide development where amidation is essential for activity/stability
Parallel or automated peptide synthesis
Peptidomimetics and combinatorial libraries
Cleavage Profile
| Reagent | Conditions | Resulting Product |
|---|---|---|
| TFA (95%) + scavengers | 1–2 hours at room temperature | Peptide–CONH₂ (amide) |
| Milder cleavage (e.g., 1–5% TFA) | Slower, selective deprotection | Useful in specialized protocols |
The increased acid lability of the Ramage linker compared to Rink Amide allows for partial deprotection or orthogonal strategies where needed.
Handling & Storage
Store dry, away from moisture and light
Swell in DMF or DCM before use
Compatible with automated and manual SPPS systems
Avoid prolonged exposure to moisture, strong acids, or bases outside standard protocols
Comparison Table
| Resin | C-Terminus | Cleavage Strength | Acid Sensitivity | Use Case |
|---|---|---|---|---|
| Ramage Amide AM | –CONH₂ | Mild (TFA) | Higher | For peptide amides with clean cleavage |
| Rink Amide AM | –CONH₂ | Moderate (TFA) | Standard | Most common for C-terminal amides |
| Wang Resin | –COOH | Strong (TFA) | Standard | C-terminal carboxylic acids |
| Sieber Amide Resin | –CONH₂ | Very mild acid | Very high | Used for acid-sensitive or protected peptides |
Conclusion
Ramage Amide AM Resin offers an ideal balance of acid-labile cleavage, Fmoc-compatibility, and robust synthesis performance for producing C-terminal peptide amides. Its ability to cleave under milder conditions than Rink Amide makes it especially valuable for sensitive sequences, difficult peptides, or strategic synthesis workflows.
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