Cyanine5 NHS ester is a ideal reactive dye for the labeling of peptides, proteins, and oligonucleotides which contain the amino-groups. Recently, among the life science research and diagnostics, Dye color quantity can be detected in gel electrophoresis by naked eye as the dye color is very intense and as small as 1 nanomol. 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. For more sophisticated targets such as easily degradable proteins, when use of DMF or DMSO is undesirable, consider using water-soluble Cy5 NHS ester which does not require co-solvent, and has very similar fluorescent properties.
