Cy5-Biotin-Azide is a trifunctional labeling reagent capable of covalently attaching to a terminal alkyne at one end. Unlike typical fluorescent labeling reagent, Cy5-Biotin-Azide also incorporates a biotin group. Together these features allow for both visualization and affinity purification of alkyne-tagged molecules.
Cy5-Biotin-Azide biotinylates only surface proteins of whole cells because the negatively charged reagent does not permeate cell membranes.