Aloc-L-Lys(Fmoc)-OH

Aloc-L-Lys(Fmoc)-OH is a lysine building block bearing both an Fmoc-protected alpha-amino group and an Aloc (allyloxycarbonyl) protecting group on the lysine side-chain, enabling orthogonal protection strategies during peptide assembly. The L-configuration and the dual protecting-group pattern make it a widely used reagent for constructing lysine-containing sequences where selective side-chain deprotection is required for subsequent functionalization or coupling. As a protected amino acid derivative, it is typically handled as a peptide synthesis intermediate rather than a free amino acid reagent.

1. Orthogonal Lysine Side-Chain

Aloc-L-Lys(Fmoc)-OH supports peptide synthesis workflows that require controlled access to the lysine side chain after the main chain has been assembled. Peptide synthesis groups use the orthogonal Aloc strategy to keep the lysine ε-amino group protected during standard coupling steps, then generate a lysine handle at a defined stage for downstream steps such as further elongation, branching, or selective attachment of functional moieties. This protection design is particularly valuable when the target sequence contains multiple reactive positions or when later-stage chemistry must be performed without disturbing other protecting groups.

2. Site-Specific Peptide Functionalization

Aloc-L-Lys(Fmoc)-OH is frequently selected for preparing peptides that carry lysine-derived modifications at a predetermined position, including conjugation-ready peptide intermediates used in chemical biology and biomaterials research. By maintaining the ε-amino group as an Aloc-protected functionality during initial assembly, researchers can perform selective side-chain unveiling to enable subsequent derivatization steps such as attachment of linkers, affinity tags, or other peptide modifications while preserving the integrity of the peptide backbone. This approach is commonly used in custom peptide synthesis when the lysine modification site must be introduced with high positional control.

3. Complex Peptide Library Synthesis

Aloc-L-Lys(Fmoc)-OH is used in peptide library construction where lysine-containing diversity is introduced after initial scaffold formation. In peptide discovery and structure-activity relationship studies, chemists often build a common protected framework first, then selectively modify the lysine side chain to generate analog sets under consistent conditions. The combination of an Fmoc-compatible backbone protection with an Aloc-protected lysine side chain helps streamline library workflows by reducing cross-reactivity during earlier synthesis cycles and enabling a uniform handle for parallel derivatization across multiple members of the library.

4. Medicinal Chemistry Intermediate Building

Aloc-L-Lys(Fmoc)-OH serves as a practical intermediate for medicinal chemistry programs that require lysine-bearing peptide fragments or peptidomimetic precursors with a controlled functionalization point. Development teams use this reagent to prepare building blocks where the lysine ε-amino functionality must remain masked during peptide fragment assembly and then be revealed for coupling to other chemical motifs. This makes it useful for constructing modified peptide intermediates used in lead optimization campaigns, where maintaining reaction compatibility across multiple synthetic stages is a key consideration.

1. Immune responses to peptides containing homocitrulline or citrulline in the DR4-transgenic mouse model of rheumatoid arthritis

2. SERS spectrum of the peptide thymosin‐β4 obtained with Ag nanorod substrate

3. A possible role of tachykinin-related peptide on an immune system activity of mealworm beetle, Tenebrio molitor L

4. GLP-1, exendin-4 and C-peptide regulate pancreatic islet microcirculation, insulin secretion and glucose tolerance in rats

5. Immune responses to homocitrulline-and citrulline-containing peptides in rheumatoid arthritis