Fmoc-Asn(Trt)-PAB is an orthogonally protected asparagine-p-aminobenzyl (PAB) linker intermediate used in self-immolative linker and targeted-delivery chemistry. The alpha amino group is Fmoc-protected, the asparagine side-chain amide is Trt-protected, and the PAB unit provides the self-immolative spacer element.

This protection pattern is well suited to stepwise linker assembly because Fmoc can be removed selectively for subsequent amino-acid or peptide extension while the Trt-protected asparagine side chain remains masked until acidic deprotection.

Product Information

Asn-PAB in Cleavable Linker Design

Asn-PAB architectures are of interest in protease-responsive delivery systems, including linker concepts designed around legumain/asparaginyl endopeptidase recognition. Enzymatic cleavage of a completed recognition motif can be coupled to self-immolative spacer chemistry to release an attached payload.

Why Use the Fmoc-Protected Form?

The Fmoc group provides a removable alpha-amino protecting group compatible with stepwise peptide-style synthesis. This allows an upstream enzyme-recognition sequence or linker component to be assembled in a controlled order. The corresponding H-Asn(Trt)-PAB has a free alpha amine and is ready for immediate coupling.

ADC, PDC and Linker-Payload Applications

Applications include preparation of protease-cleavable linker candidates, self-immolative ADC/PDC intermediates, linker-payload standards and research conjugates for cleavage/selectivity optimization. The exact cleavage kinetics and payload-release behavior depend on the full linker and conjugate architecture.

Assay Relevance

After construction of the complete conjugate, downstream studies may include purified-enzyme cleavage assays, lysosomal stability, plasma stability, payload-release analysis, cell-based potency and in vivo pharmacology. Fmoc-Asn(Trt)-PAB itself is a protected synthetic intermediate rather than a direct assay reagent.

Product Documents

A Material Safety Data Sheet (MSDS) is available for this product to support laboratory handling, storage and safety assessment.

MSDS_Fmoc-Asn-Trt--PAB_AS4057

Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.

Frequently Asked Questions

What is the difference between Fmoc-Asn(Trt)-PAB and H-Asn(Trt)-PAB?

The Fmoc form has a protected alpha amine for controlled stepwise assembly. The H- form has a free alpha amine and is ready for direct coupling.

Is PAB a self-immolative spacer?

Yes. PAB-derived spacers are widely used in self-immolative linker designs, where upstream enzymatic or chemical cleavage can trigger downstream payload release.

Does this product guarantee legumain cleavage?

No. Enzyme recognition and cleavage must be evaluated using the completed linker or conjugate. The isolated building block provides a synthetic component of that architecture.

Related Technical Resources

Browse Specialty Peptide Building Blocks or discuss custom linker synthesis through Chemical Peptide Synthesis.

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