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Cy5

Cy5 (Ex-Max 649 nm/Em-Max 667 nm)

Cy5 is an important historical fluorophore from GE Healthcare. It has an excitation peak at 649 nm and an emission peak at 667 nm. Spectrally its similar to Alexa Fluor™ 647.

Excitation & emission spectra

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Key facts

Excitation maximum
649 nm
Emission maximum
667 nm
Optimal laser line
628-640
Optimal filter
660/20
Extinction coefficient
250000
Quantum yield
0.27
Molecular weight
1500
Commercial conjugates
6.2k from 24 suppliers

Cy5 has an excitation maximum at 649 nm and an emission maximum at 667 nm, a Stokes shift of 18 nm. Its extinction coefficient is 250000 M⁻¹cm⁻¹. It is optimally excited by the 628-640 laser line.

Frequently asked questions

What is Cy5?
Cy5 is an important historical fluorophore from GE Healthcare. It has an excitation peak at 649 nm and an emission peak at 667 nm. Spectrally its similar to Alexa Fluor™ 647.
What laser excites Cy5?
Cy5 is optimally excited by the 628-640 laser line. Its excitation maximum is 649 nm.
What filter should I use to detect Cy5?
A 660/20 filter captures the peak of the Cy5 emission near 667 nm with minimal spillover.
How many antibodies are available conjugated to Cy5?
FluoroFinder tracks 6195 commercially available Cy5 conjugates, searchable by target, clone, host and application.