Fluorescein isothiocyanate

Fluorescein isothiocyanate

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Names
Other names FITC
Identifiers
CAS Number	27072-45-3 Y
ChEBI	CHEBI:37928 Y
ChemSpider	2043359 Y
Jmol 3D model	Interactive image
MeSH	Fluorescein-5-isothiocyanate
PubChem	18730
InChI InChI=1S/C21H11NO5S/c23-12-2-5-15-18(8-12)26-19-9-13(24)3-6-16(19)21(15)17-7-11(22-10-28)1-4-14(17)20(25)27-21/h1-9,23-24H Y Key: GTQFZXYECNSNNC-UHFFFAOYSA-N Y InChI=1/C21H11NO5S/c23-12-2-5-15-18(8-12)26-19-9-13(24)3-6-16(19)21(15)17-7-11(22-10-28)1-4-14(17)20(25)27-21/h1-9,23-24H Key: GTQFZXYECNSNNC-UHFFFAOYAK
SMILES S=C=Nc5cc1c(C(=O)OC13c4ccc(O)cc4Oc2cc(O)ccc23)cc5
Properties
Chemical formula	C21H11NO5S
Molar mass	389.382
Density	1.542 g/mL
Melting point	359.5 °C (679.1 °F; 632.6 K)
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Fluorescein isothiocyanate (FITC) is a derivative of fluorescein used in wide-ranging applications including flow cytometry. FITC is the original fluorescein molecule functionalized with an isothiocyanate reactive group (-N=C=S), replacing a hydrogen atom on the bottom ring of the structure. This derivative is reactive towards nucleophiles including amine and sulfhydryl groups on proteins.

A succinimidyl-ester functional group attached to the fluorescein core, creating "NHS-fluorescein", forms another common amine reactive derivative that has much greater specificity toward primary amines in the presence of other nucleophiles.

FITC has excitation and emission spectrum peak wavelengths of approximately 495 nm/519 nm. Like most fluorochromes, it is prone to photobleaching. Because of the problem with photobleaching, derivatives of fluorescein such as Alexa 488 and DyLight 488 have been tailored for various chemical and biological applications where greater photostability, higher fluorescence intensity, or different attachment groups are needed.