Dawson Dbz AM Resin (100–200 Mesh): Advanced Resin for Peptide Thioester and Ligation Chemistry
Dawson Dbz AM Resin is a specialized polystyrene resin designed for the Fmoc-based synthesis of peptide hydrazides and thioesters, which are essential precursors for native chemical ligation (NCL). It is functionalized with a 3,4-diaminobenzoic acid (Dbz) linker, originally developed by Dr. Philip Dawson’s group, and is attached to an aminomethylated (AM) polystyrene resin base. The resin allows for the synthesis of C-terminal peptide thioesters via a mild post-cleavage activation process, typically through acyl azide formation or on-resin cyclization to form the N-acylurea derivative.
Specifications
Matrix: Polystyrene cross-linked with ~1% DVB
Linker: 3,4-diaminobenzoic acid (Dbz)
Base: Aminomethylated polystyrene (AM resin)
Loading: Typically 0.4–0.8 mmol/g
Particle Size: 100–200 mesh (approx. 75–150 µm)
Cleavage: TFA-based, followed by post-cleavage activation
Compatible Chemistry: Fmoc/tBu peptide synthesis
Target Product: Peptide thioesters or hydrazides (via further conversion)
Key Features
Enables Peptide Thioester Synthesis: Critical for native chemical ligation (NCL)
Mild Cleavage Conditions: TFA-compatible for routine peptide workflows
Fmoc-Compatible: Integrates smoothly into standard SPPS protocols
High Stability: Resistant to premature cleavage or degradation
Versatile Applications: Can be converted into thioesters, acyl azides, or N-acylureas
Applications
Native chemical ligation (NCL)
Peptide thioester synthesis
Peptide hydrazide intermediates
Semisynthesis of proteins and cyclic peptides
Chemical protein engineering and fragment ligation
Mechanism & Conversion
After synthesis, the Dbz-linked peptide is cleaved from the resin using standard TFA cocktails. Post-cleavage, it can be:
Converted to a peptide thioester via:
N-acylurea formation (Dbz → Nbz) followed by thiolysis
In-solution activation using sodium nitrite (NaNO₂) to form an acyl azide, then reaction with a thiol
Used as a peptide hydrazide (after further derivatization of the Dbz group), serving as a stable thioester precursor.
Cleavage & Activation Overview
| Step | Reagent/Condition | Product Form |
|---|---|---|
| Cleavage from resin | 95% TFA with scavengers | Peptide-Dbz (free acid form) |
| Cyclization (on-resin or in-solution) | Carbodiimide (e.g., DIC) or NaNO₂ activation | N-acylurea or acyl azide |
| Thiolysis | MESNa, MPAA, etc. | Peptide thioester |
Handling & Storage
Store dry and protected from moisture
Swell in DMF or DCM before use
Handle under standard SPPS protocols
Compatible with automated and manual synthesizers
Comparison With Related Resins
| Resin | Functionality | Final Product | NCL Compatible |
|---|---|---|---|
| Dawson Dbz AM Resin | Dbz → Nbz / thioester | Peptide thioester | Yes |
| Hydrazine Resin | –NHNH₂ | Peptide hydrazide | Yes (via oxidation) |
| 2-Chlorotrityl Resin | Acid-labile aryl ether linker | Peptide acid | No |
| Rink Amide AM Resin | Amide linker | Peptide amide | No |
Conclusion
Dawson Dbz AM Resin (100–200 mesh) is a cutting-edge tool for synthetic peptide chemistry, enabling efficient access to peptide thioesters and hydrazides under Fmoc-compatible conditions. It plays a critical role in modern ligation techniques such as native chemical ligation, making it essential for chemical biology, protein engineering, and peptidomimetic design
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