Cy3 and Cy5
Cy 3 and Cy5 are the most popular Cyanine dyes, used typically combined for 2 color detection. Cy3 dyes fluoresce yellow-green (~550 nm excitation, ~570 nm emission), while Cy5 is fluorescent in the red region (~650/670 nm) but absorbs in the orange region (~649 nm).
They are usually synthesized with reactive groups on either one or both of the nitrogen side chains so that they can be chemically linked to either nucleic acids or protein molecules. Labeling is done for visualization and quantification purposes. They are used in a wide variety of biological applications including comparative genomic hybridization and in gene chips, which are used in transcriptomics. They are also used to label proteins and nucleic acid for various studies including proteomics and RNA localization.
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