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5-FAM Cysteamine

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Physical properties
Molecular weight435.45
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
5-Carboxyfluorescein (also known as 5-FAM or 5-Fluorescein) is a fluorescent dye commonly used in molecular biology and biochemistry research. It belongs to the family of fluorescein derivatives and is often used as a fluorescent label or tracer in various applications. 5-FAM cysteamine contains a free thiol group that readily reacts with maleimide and other SH-reactive groups such as iodoacetamide and vinyl sulfone etc. It is an excellent building block for developing fluorescent probes with maleimide-modified biomolecules. The resulting probes exhibit strong fluorescence when excited with light in the blue to green spectral range (absorption maximum at approximately 495 nm and emission maximum at approximately 520 nm). Due to its bright fluorescence, stability, and compatibility with various detection systems, 5-FAM probes are widely used as fluorescent labels for biomolecules. Overall, 5-Carboxyfluorescein is a versatile and widely used fluorescent dye in molecular biology research, offering excellent brightness and compatibility with various labeling and detection methods. Its fluorescent properties make it a valuable tool for visualizing and studying biological molecules and processes. It can be employed to label nucleotides, oligonucleotides, peptides, proteins, antibodies, or other molecules of interest. The labeled molecules can be visualized and detected using fluorescence microscopy, flow cytometry, or other fluorescence-based techniques.


Common stock solution preparation

Table 1. Volume of DMF needed to reconstitute specific mass of 5-FAM Cysteamine to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM229.647 µL1.148 mL2.296 mL11.482 mL22.965 mL
5 mM45.929 µL229.647 µL459.295 µL2.296 mL4.593 mL
10 mM22.965 µL114.824 µL229.647 µL1.148 mL2.296 mL

Molarity calculator

Enter any two values (mass, volume, concentration) to calculate the third.

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Product Family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Correction Factor (260 nm)Correction Factor (280 nm)
5(6)-FAM [5-(and-6)-Carboxyfluorescein] *CAS 72088-94-9*493517830000.320.178
5-FAM, SE [5-Carboxyfluorescein, succinimidyl ester] *CAS 92557-80-7*493517830000.320.178
5-FAM ethylenediamine493517830000.320.178
5-FAM cadaverine493517830000.320.178
5-FAM Azide493517830000.320.178
5-FAM Alkyne493517830000.320.178



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