Biotin-4-fluorescein *CAS 1032732-74-3*

Biotin-4-fluorescein

CAS 1032732-74-3

This bifunctional biotin-fluorescein conjugate demonstrates better binding and stronger fluorescence than biotin fluorescein. It has similar avidin-binding properties in terms of high affinity, fast association, and non-cooperative binding to avidin and streptavidin tetramers. These exceptional properties are attributed to the small size/length of the new ligand since all larger/longer biotin derivatives are known for their mutual steric hindrance and anti-cooperative binding in 4:1 complexes with avidin and streptavidin tetramers. Specific binding of this biotin-fluorescein conjugate towards avidin and streptavidin is accompanied by 84-88% quenching of ligand fluorescence. It is used for the quantitation of biotin-binding sites. Both the fluorescence and absorbance of biotin-4-fluorescein are quenched upon binding to one of the four biotin-binding sites of streptavidin, avidin, or the streptavidin conjugates of fluorescent dyes or enzymes. As a result, when a known concentration of biotin-4-fluorescein is added to a known amount of streptavidin, one can estimate the number of biotin-binding sites.

Catalog	Size	Price	Quantity
3006	5 mg	Price

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of Biotin-4-fluorescein *CAS 1032732-74-3* to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

	0.1 mg	0.5 mg	1 mg	5 mg	10 mg
1 mM	155.113 µL	775.567 µL	1.551 mL	7.756 mL	15.511 mL
5 mM	31.023 µL	155.113 µL	310.227 µL	1.551 mL	3.102 mL
10 mM	15.511 µL	77.557 µL	155.113 µL	775.567 µL	1.551 mL

Molarity calculator

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

Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
mg	÷	644.69 g/mol	=	mL	x	mM	=	mmol

References

View all 17 references: Citation Explorer

Engineered single-chain dimeric streptavidins with an unexpected strong preference for biotin-4-fluorescein

Authors:

Aslan FM, Yu Y, Mohr SC, Cantor CR.

Journal:

Proc Natl Acad Sci U S A (2005): 8507

Dynamics of fluorescence dequenching of ostrich-quenched fluorescein biotin: a multifunctional quantitative assay for biotin

Authors:

Wu Y, Simons PC, Lopez GP, Sklar LA, Bur and a T., undefined

Journal:

Anal Biochem (2005): 221

Preparation and characterisation of antibody modified gelatin nanoparticles as drug carrier system for uptake in lymphocytes

Authors:

Balthasar S, Michaelis K, Dinauer N, von Briesen H, Kreuter J, Langer K.

Journal:

Biomaterials (2005): 2723

Electrophoretic behavior of streptavidin complexed to a biotinylated probe: a functional screening assay for biotin-binding proteins

Authors:

Humbert N, Zocchi A, Ward TR.

Journal:

Electrophoresis (2005): 47

Controlled surface functionalization of silica nanospheres by covalent conjugation reactions and preparation of high density streptavidin nanoparticles

Authors:

Schiestel T, Brunner H, Tovar GE.

Journal:

J Nanosci Nanotechnol (2004): 504

Physical properties

Molecular weight	644.69
Solvent	DMSO

Spectral properties

Absorbance (nm)	487
Correction factor (260 nm)	0.32
Correction factor (280 nm)	0.35
Extinction coefficient (cm ^-1 M ^-1)	80000 ¹
Excitation (nm)	498
Emission (nm)	517
Quantum yield	0.7900 ¹ , 0.95 ²

Storage, safety and handling

Certificate of Origin	Download PDF
H-phrase	H303, H313, H333
Hazard symbol	XN
Intended use	Research Use Only (RUO)
R-phrase	R20, R21, R22
Storage	Freeze (< -15 °C); Minimize light exposure; Desiccated
UNSPSC	12352200
CAS	1032732-74-3

Instrument settings

Fluorescence microplate reader
Excitation	492 nm
Emission	518 nm
Cutoff	500 nm
Recommended plate	Solid black

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Page updated on October 13, 2025