H-Cit-AMC

H-Cit-AMC is a citrulline-derived amino acid amide linked to the 7-amino-4-methylcoumarin (AMC) fluorophore, forming a chiral amino acid building block that bears a free ureido-type side chain functionality characteristic of citrulline. The molecule contains an amide bond connecting the citrulline nitrogen to the AMC moiety, while the coumarin chromophore provides strong fluorescence upon cleavage of the AMC reporter. The stereochemistry at the citrulline alpha-carbon is retained from the chiral amino acid precursor, enabling consistent recognition in enzyme-active-site contexts and supporting stereochemically defined substrate design. H-Cit-AMC therefore functions as a chemically stable, labeled intermediate that can be incorporated into biochemical assays, used to generate structurally related citrulline derivatives, and further transformed through amide/ureido chemistry typical of amino acid derivative workflows.

1. Enzyme Substrate Assays

H-Cit-AMC is applied in enzyme kinetics and chemical biology workflows where citrulline-dependent proteolysis or deamidation events generate fluorescent AMC. The citrulline side chain and the amide-linked AMC reporter create a substrate-like structure that participates in enzyme recognition while translating cleavage into a measurable optical signal. The coumarin fluorophore enables downstream analytical readouts without requiring additional derivatization steps, supporting studies of enzyme specificity, inhibitor screening, and mechanistic comparisons across related amino acid substrates. The chiral amino acid backbone helps maintain stereochemical fidelity in substrate-enzyme interactions, making H-Cit-AMC suitable for generating quantitative data that reflect amino acid chemistry rather than nonspecific labeling.

2. Peptidomimetic Building Blocks

H-Cit-AMC is utilized in peptidomimetic construction and molecular design efforts that require citrulline-mimicking motifs coupled to a cleavable reporter handle. The ureido functionality of the citrulline residue and the amide linkage to AMC provide a compact scaffold that can be adapted into longer conjugates or used as a reference point for side-chain functionalization strategies. The coumarin reporter can be retained for traceable cleavage studies or replaced through controlled functional group transformations to furnish non-fluorescent analogs for structure-activity relationship studies. The defined stereocenter at the amino acid alpha-carbon supports consistent conformational and recognition properties when assembling citrulline-containing analog series.

3. Protein Engineering Tools

H-Cit-AMC is suitable for protein engineering and enzyme engineering contexts that require fluorescent readouts tied to citrulline processing or site-selective substrate turnover. The amino acid amide architecture allows the labeled citrulline unit to be treated as a defined chemical probe, enabling mapping of substrate preferences for engineered variants that recognize citrulline-like side chains. The AMC fluorophore supports monitoring of cleavage or release events in a manner compatible with iterative design cycles for substrate specificity and catalytic efficiency comparisons. The presence of a stable amide and the preserved chiral configuration make H-Cit-AMC a consistent chemical input for generating structure-function datasets in applied protein chemistry.

4. Analytical Fluorescent Standards

H-Cit-AMC is applied in analytical research as a fluorescence-active amino acid derivative standard for validating assay conditions and calibrating reporter response. The coumarin chromophore provides a direct optical handle, while the citrulline-derived portion gives a chemically defined reference that aligns with amino acid derivatization and cleavage-based measurement schemes. The labeled amide structure can be used to benchmark signal generation, support method development for fluorescence detection, and enable comparative quantitation across related citrulline substrates. The chiral amino acid origin supports reproducible behavior in workflows where stereochemistry influences cleavage patterns or background signals.

5. Process Chemistry Intermediate

H-Cit-AMC serves as a practical intermediate in fine chemical synthesis and process chemistry routes targeting citrulline-labeled reagents and coumarin-based reporter conjugates. The molecule's functional group set, including the amide linkage and ureido-type side chain, supports downstream transformations toward alternative protecting-group strategies, reporter substitutions, or conversion to other citrulline derivatives. The defined AMC moiety can be used to design manufacturing workflows that emphasize controlled coupling chemistry and stable labeled products for biochemical use. The chiral amino acid framework supports stereochemically consistent batch production of citrulline analogs used in analytical and research-grade reagent supply chains.

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

2. Proinsulin C-peptide and insulin: Limited pattern similarities of interest in inter-peptide interactions but no C-peptide effect on insulin and IGF-1 receptor signaling

3. Adipose tissue is a key organ for the beneficial effects of GLP-2 metabolic function

4. Emerging applications of nanotechnology for diagnosis and therapy of disease: a review

5. Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae)