Cy5 maleimide (non-sulfonated)

Cy5 maleimide is a mono-reactive dye for selectively labeling peptides and proteins which couples with thiol groups. The labeling reagent is a common fluorophore dye with low aqueous solubility which is compatible with various instrumentation like microscopes, imagers, and fluorescence readers. Cy5 maleimide is part of the probe among the biological research. For biomolecule labeling, the labeling reagent has low aqueous solubility, using of organic co-solvent to dissolve this molecular is necessary for efficient reaction. First, Cyanine dye should be dissolved in organic solvent and then added to a solution of biomolecule in appropriate aqueous buffer. The user can generate probes with virtually any non-genetically encoded moiety of interest with the scaffold in hand.

G3C(Cy5) probe consists of two parts. First, a GGGC scaffold peptide is synthesized on solid phase, followed by coupling of the liberated peptide to Cy5 maleimide, while in solution [1].

Reference:
[1].  Popp, M.W. Site-Specific Labeling of Proteins via Sortase: Protocols for the Molecular Biologist. Methods in Molecular Biology,2015, 1266, 185–198.