Basic Chemical Information

Fmoc-Lys(Pal-Glu-OtBu)-OH is an Fmoc-protected lysine derivative with CAS number 1491158-62-3. Its molecular formula is C₄₆H₆₉N₃O₈ and molar mass is 792.07 g/mol. It appears as a white to off-white powder. The “Fmoc” (9-fluorenylmethoxycarbonyl) group protects the amino end of lysine during synthesis. The lysine side chain (ε-amino group) is linked to a palmitoyl-glutamate unit, where glutamic acid’s side-chain carboxyl is tert-butyl-protected (OtBu). This design combines a long lipid chain (palmitoyl, C16) with a protected carboxyl, making the molecule more hydrophobic. As an amino acid derivative, it serves as a building block in solid-phase peptide synthesis (SPPS).

Structural Features and Properties

Fmoc-Lys(Pal-Glu-OtBu)-OH has three key parts: the Fmoc protecting group, the lysine backbone, and the Pal-Glu(OtBu) side chain. The Fmoc blocks the α-amino of lysine, while a palmitoylated glutamate is attached to the ε-amine of lysine. The glutamate is further protected by a tert-butyl ester (OtBu) on its α-carboxyl group. Together, these features create a bulky, hydrophobic side chain. For example, liraglutide (a GLP-1 analog drug) is a 31-amino acid peptide that is branched at lysine-27 with a palmitoyl-γ-glutamate moiety. Attaching palmitic acid via a glutamate linker dramatically increases peptide half-life; for liraglutide, this modification raises its half-life from minutes to hours.

Role in Peptide Synthesis

In SPPS, Fmoc-Lys(Pal-Glu-OtBu)-OH is used like a standard Fmoc-amino acid. The Fmoc on the N-terminus is removed (typically with piperidine) to expose the α-amine for coupling. The side-chain palmitoyl-glutamate remains intact (with its OtBu protection) during chain assembly. This allows a peptide elongation strategy where lipidation is pre-installed on lysine. For instance, to synthesize liraglutide, one would couple Fmoc-Lys(Pal-Glu-OtBu)-OH at the appropriate step. After complete assembly, global deprotection yields the peptide with the free γ-glutamate (and attached palmitoyl) at Lys-27. This way, the long palmitoyl chain is built in seamlessly. Chengdu Pukang offers this high-purity intermediate to streamline such processes.

Research and Unique Applications

Beyond GLP-1 analogs, Fmoc-Lys(Pal-Glu-OtBu)-OH is valuable in designing lipidated peptides and bioconjugates. Peptide lipidation (attachment of fatty acids) is known to improve drug stability and membrane affinity. For example, the palmitoyl-Glu attachment in liraglutide extends its subcutaneous half-life to about 13 hours. Similar strategies are used in other peptide drugs (e.g., semaglutide and insulin detemir) to lengthen activity. In research, this intermediate also serves as a hydrophobic linker: it has been noted as a non-cleavable linker in antibody-drug conjugates (ADCs) and as an alkyl chain linker in PROTACs. These applications exploit its stable C16 chain and protected carboxylate to join drug moieties or target ligands without premature cleavage. In summary, Fmoc-Lys(Pal-Glu-OtBu)-OH is a versatile building block for crafting peptides and conjugates with enhanced lipophilicity and stability.

Solubility and Storage

Because of its long fatty chain, Fmoc-Lys(Pal-Glu-OtBu)-OH is practically insoluble in water. It dissolves well in polar organic solvents such as DMF or DMSO, which are commonly used for peptide coupling. In practice, chemists prepare concentrated stock solutions in DMSO or DMF. It is best to aliquot these stocks and keep them frozen to avoid repeated freeze–thaw cycles. The solid should be stored cold (2–8 °C) and protected from moisture. Chengdu Pukang’s product page also advises refrigeration (2–8 °C) for the dry powder. Following these guidelines preserves the stability of the Fmoc group and tert-butyl ester until use.

Related Chengdu Pukang Products

Chengdu Pukang offers a variety of related peptide intermediates alongside Fmoc-Lys(Pal-Glu-OtBu)-OH. Notable related items include:

• Pal-Glu(OH)-OtBu: tert-butyl protected palmitoyl-glutamic acid.

• Pal-Glu(OSu)-OtBu: activated ester of palmitoyl-Glu(OtBu) for coupling.

• Pal-Glu(OSu)-OH: palmitoyl-glutamate pentafluorophenyl ester (no OtBu).

• Fmoc-Lys-OH·HCl: standard Fmoc-lysine for peptides.

These building blocks support long-acting peptide design, especially GLP-1 analogs. Chengdu Pukang highlights that it provides side-chain modifiers for modern peptide drugs. Their catalog includes GLP-1 analog side chains like liraglutide, semaglutide, and others. The peptide modifier platform is built to accelerate peptide drug development with pre-made lipidated amino acids and analogs.

You can explore this product directly here: https://peglinke.com/liraglutide-intermediates/1491158-62-3.html

For official compound reference, see:

• PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/1491158-62-3

• ChemSpider: https://www.chemspider.com/Chemical-Structure.57455151.html

Overall, Fmoc-Lys(Pal-Glu-OtBu)-OH is a high-quality peptide intermediate tailored for modern therapeutics. Chengdu Pukang’s offering of this compound (≥98% purity, cold-chain shipping, and large stock) makes it a convenient choice for researchers and manufacturers working on GLP-1 drugs and other lipidated peptides.