FAM isothiocyanate (FITC), 5- and 6-isomers | CAS 27072-45-3

FAM isothiocyanate (FITC), 5- and 6-isomers is a fluorescein-based isothiocyanate labeling reagent used to introduce a bright green fluorophore into biomolecules through nucleophilic addition to primary amines. The dye's widely used excitation/emission profile makes it a standard choice for fluorescence microscopy, flow cytometry, and fluorescence readouts in biochemical assays, while the isothiocyanate functional group enables covalent attachment to proteins, peptides, and other amine-containing targets. Because the product is provided as 5- and 6-isomer forms, it is frequently selected when robust fluorescein labeling performance and established workflow compatibility are prioritized.

1. Protein And Antibody Labeling

FAM isothiocyanate (FITC), 5- and 6-isomers is frequently used by immunology and protein chemistry groups to generate FITC-labeled antibodies, antibody fragments, and affinity reagents for fluorescence-based binding studies. Covalent coupling to lysine residues and N-termini supports stable fluorescent conjugates for immunostaining workflows, antigen-binding assays, and fluorescence microscopy of labeled targets. Researchers also use FITC-labeled proteins as fluorescent tracers in binding and uptake experiments, where amine-reactive labeling provides a straightforward route to fluorescent conjugates compatible with standard FITC filter sets.

2. Fluorescence Microscopy Staining

FAM isothiocyanate (FITC), 5- and 6-isomers is commonly selected for cellular and molecular staining protocols that rely on fluorescein fluorescence to visualize labeled biomolecules in fixed samples. In microscopy workflows, FITC conjugates prepared from amine-containing targeting reagents (such as labeled proteins, lectins, or secondary antibodies) are used to map localization of extracellular markers, cell-surface components, and macromolecular assemblies. The reagent format supports downstream conjugate preparation for immunofluorescence staining, enabling consistent visualization on epifluorescence and confocal instruments configured for fluorescein detection.

3. Flow Cytometry Fluorescent Labeling

FAM isothiocyanate (FITC), 5- and 6-isomers is widely used in flow cytometry reagent development to produce FITC-labeled antibodies and protein probes for fluorescence-activated cell analysis. Amine-reactive labeling supports the preparation of fluorescent conjugates used for cell-surface marker staining, receptor binding readouts, and quantitative fluorescence tracking of labeled biomolecules in heterogeneous cell populations. In multiplex experimental designs, FITC-labeled reagents are often paired with other fluorophores using instrument-specific compensation strategies, leveraging the reagent's compatibility with common FITC detection channels.

4. Fluorescent Bioassay Tracers

FAM isothiocyanate (FITC), 5- and 6-isomers is frequently incorporated into fluorescence bioassay development where FITC-labeled proteins or peptides act as tracers to monitor binding, competition, or labeling-dependent signal generation. Assay developers use FITC conjugates to follow biomolecular interactions in solution or on assay surfaces, including fluorescence-based binding measurements and fluorescence readouts in microplate formats. The isothiocyanate functionality enables preparation of amine-labeled assay reagents that can be standardized for routine screening workflows and imaging-assisted endpoint assays.