Product Description: Cy5-PEG2-SCO is a dye derivative of Cyanine 5 (Cy5) (HY-D0821) containing 2 PEG units. Cy5-PEG2-SCO has a SCO group that can be covalently bonded to the amino group. SCO is often used to react with amino acid residues of proteins or peptides, particularly lysine.