Product Description: Cy3-PEG2-SCO is a dye derivative of Cyanine 3 (Cy3) (HY-D0822) containing 2 PEG units. Cy3-PEG2-SCO carries a SCO group that can be covalently bound to an amino group. SCO is often used to react with amino acid residues of proteins or peptides, particularly lysine.