Fmoc-Phe-Lys(Trt)-OH is a preassembled protected L-Phe-Lys dipeptide carrying an N-terminal Fmoc group and a trityl-protected lysine side-chain amino function, as indicated by the product name. It provides a defined Phe-Lys junction for fragment-based peptide synthesis and for research on protease-cleavable linker motifs.

Phe-Lys is historically important in enzyme-cleavable conjugate chemistry: cathepsin-sensitive Phe-Lys linker systems have been studied as peptide triggers for intracellular payload release. The Trt protection on lysine allows the side-chain amine to remain masked during selected synthetic operations and can support orthogonal downstream functionalization.

Product Information

Why Use a Preassembled Phe-Lys Fragment?

A preassembled dipeptide locks the sequence order and stereochemical assignment before it is incorporated into a larger construct. It can remove one amino-acid coupling step and can be useful when the Phe-Lys junction is a defined element of a peptide linker, modified peptide or fragment-coupling route.

For customers searching Phe-Lys ADC linker, cathepsin-cleavable dipeptide or Fmoc-Phe-Lys building block, the key distinction is that this product is a protected synthetic precursor, not a completed linker-payload or antibody conjugate.

Phe-Lys in Protease-Cleavable Linker Research

Peptide-linker literature has evaluated Phe-Lys as a protease-sensitive dipeptide trigger. In early comparative studies, Phe-Lys-containing constructs showed rapid enzymatic cleavage, although plasma stability and overall performance depend strongly on neighboring spacer chemistry and the full conjugate design.

Accordingly, the protected Phe-Lys fragment can support linker SAR, but enzyme selectivity, plasma stability and intracellular release must be measured on the final construct rather than assumed from the dipeptide alone.

Why Trt-Protect the Lysine Side Chain?

Lysine contains both an alpha-amino group and an epsilon side-chain amino group. Selective side-chain protection prevents unintended acylation during fragment assembly. Trityl protection is acid-labile and provides a protection profile different from the more common Lys(Boc) building blocks.

Because Lys(Trt) is less common than Lys(Boc), procurement should confirm the exact protected nitrogen and cleavage strategy from the lot-specific structural documentation before planning an orthogonal synthesis.

Application Scope

Potential applications include fragment-based peptide synthesis, protease-cleavable linker development, ADC/PDC linker SAR, lysine-selective conjugation workflows, cyclic or branched peptide assembly and modified peptide synthesis.

Final linker constructs can be evaluated using protease-cleavage assays, plasma-stability studies, lysosomal processing experiments and cell-based payload-release assays as appropriate.

Purchasing and QC Considerations

Because no reliable public CAS assignment was confirmed, use AS4070, the full Fmoc-Phe-Lys(Trt)-OH name, molecular formula, molecular weight and lot-specific COA to verify identity. Confirm L/L stereochemistry, Trt location and chemical purity before use.

Product Documents

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

MSDS_Fmoc-Phe-Lys-Trt-OH_AS4070

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

Is Phe-Lys used in cleavable linker research?

Yes. Phe-Lys has been investigated as a protease-sensitive dipeptide trigger, but cleavage and stability are properties of the complete linker architecture.

Why is lysine Trt-protected?

Side-chain protection prevents unwanted reaction of the lysine epsilon amine and can provide an orthogonal handle for later functionalization.

Is this product a finished ADC linker?

No. It is a protected dipeptide building block used to construct larger peptide-linker systems.

Related Technical Resources

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