Fluorescein isothiocyanate isomer I (CAS 3326-32-7)

Fluorescein isothiocyanate isomer I, commonly abbreviated as FITC and recognized by the CAS number 3326-32-7, is a derivative of fluorescein, extensively used in various fields of biotechnological and biochemical research, particularly in the area of fluorescent labeling. This compound is characterized by its bright green fluorescence, which makes it an ideal marker for visualizing and tracking biological molecules under a fluorescence microscope. The core mechanism by which FITC operates involves the covalent attachment of the isothiocyanate group to amino groups in proteins or other biomolecules. This reaction typically occurs at the N-terminus or at lysine residues of proteins, forming a stable thiourea linkage. This property allows FITC to be widely used in the conjugation of antibodies, peptides, and probes in techniques such as flow cytometry, immunofluorescence, and enzyme-linked immunosorbent assays (ELISA). The fluorescence emitted by FITC-conjugated compounds enables researchers to detect the presence, location, and quantification of the labeled molecules, providing critical data in the study of cellular functions, protein interactions, and signaling pathways.