H-L-Trp(For)-OH*HCl

H-L-Trp(For)-OH*HCl is an N-protected amino acid derivative consisting of L-tryptophan bearing a formyl (For) substituent on the indole nitrogen and presented as the hydrochloride salt, which increases handling stability and water compatibility for synthetic workflows. The molecule retains the chiral amino acid stereocenter at the α-position and includes a free carboxylic acid functionality suitable for peptide bond formation, while the indole system is electronically modulated by N-formylation and can participate in controlled reactivity during downstream transformations. The salt form (HCl) enables reproducible coupling conditions and can mitigate base sensitivity of the amino group during protected amino acid synthesis. The combination of stereochemical definition, carboxylic acid reactivity, and indole N-protection makes H-L-Trp(For)-OH*HCl a practical chiral intermediate for peptide building block preparation and for indole-selective derivatization strategies.

1. Peptide Synthesis

H-L-Trp(For)-OH*HCl is applied in peptide synthesis as a tryptophan-containing chiral building block where the α-carboxylic acid can be activated for amide bond formation under standard coupling chemistries. The L-configuration provides stereochemical fidelity at the residue level, while the indole N-formyl group helps control indole nucleophilicity and can reduce side reactions such as undesired indole participation during coupling and deprotection sequences. The hydrochloride salt form supports consistent handling and can facilitate incorporation into automated or batch peptide assembly workflows that rely on reproducible amino acid salt behavior. The resulting Trp(For)-containing peptides can be further processed to generate indole-unprotected tryptophan residues or to introduce indole-functionalized analogs for peptide library construction.

2. Side-Chain Functionalization

H-L-Trp(For)-OH*HCl supports side-chain functionalization workflows targeting the indole moiety by using the N-formyl substituent as a temporary protection handle. The protected indole nitrogen modulates electrophilicity and nucleophilicity, enabling selective transformations on the indole ring or controlled deprotection to reveal the indole for subsequent derivatization steps. The free carboxylic acid and defined stereochemistry allow the compound to be converted into intermediate derivatives that can be carried into peptide analog synthesis or small-molecule conjugate preparation. Downstream use can include generation of indole-bearing fragments for SAR studies, chemical probes, or peptidomimetic scaffolds where indole reactivity must be scheduled relative to other functional group operations.

3. Chemical Biology Probes

H-L-Trp(For)-OH*HCl is suitable for chemical biology research where tryptophan-based residues serve as handles for molecular recognition, fluorescence or affinity probe design, and site-specific labeling strategies. The indole N-formyl protection can be used to manage reactivity during synthesis of probe conjugates, while the L-tryptophan backbone ensures compatibility with peptide coupling to generate defined probe architectures. The hydrochloride salt form can be advantageous when preparing aqueous-compatible intermediates for conjugation workflows that require stable amino acid derivatives. The compound can be employed to build tryptophan-containing peptides or peptide mimics that function as biochemical research tools, including substrates or binding elements for studying protein-ligand interactions.

4. SAR Studies

H-L-Trp(For)-OH*HCl is used in structure-activity relationship studies as a chiral tryptophan intermediate for constructing analog series with controlled indole protection states. The stereochemical integrity of the L-α-center and the presence of a carboxylic acid enable systematic synthesis of peptide-like scaffolds where tryptophan position and indole handling are varied without altering the residue configuration. The N-formyl group can be retained or removed depending on the desired chemical environment, supporting SAR designs that probe how indole electronics and accessibility affect binding or reactivity in biochemical assays. The resulting tryptophan-containing analogs can be carried into downstream purification, characterization, and comparative structure-function evaluation within medicinal chemistry and biochemical screening programs.

5. Pharmaceutical Intermediate Preparation

H-L-Trp(For)-OH*HCl can serve as a process-relevant pharmaceutical intermediate for manufacturing of tryptophan-containing peptide intermediates and peptidomimetic fragments. The defined L-configuration and carboxylic acid functionality allow incorporation into protected amino acid sequences that align with industrial peptide synthesis planning, where orthogonal protection and scheduled deprotection are required to maintain indole integrity. The indole N-formyl substituent provides a protection strategy that can reduce side reactions during intermediate formation and can be compatible with downstream conversion to indole-unprotected products when deprotection conditions are applied. The hydrochloride salt form supports practical isolation and feed preparation for fine chemical synthesis routes that require stable chiral amino acid inputs for controlled downstream transformations.

1. Genetic, cellular, and structural characterization of the membrane potential-dependent cell-penetrating peptide translocation pore

2. Relatedness of antibodies to peptides containing homocitrulline or citrulline in patients with rheumatoid arthritis

3. Exosomes-mediated Transfer of miR-125a/b in Cell-to-cell Communication: A Novel Mechanism of Genetic Exchange in the Intestinal Microenvironment

4. Effect of Probiotic Lactobacillus plantarum on Streptococcus mutans and Candida albicans Clinical Isolates from Children with Early Childhood Caries

5. The effect of sex on immune responses to a homocitrullinated peptide in the DR4-transgenic mouse model of Rheumatoid Arthritis