Cy5 Protein Labeling Kit

Fluorescence techniques have become a major tool in biological sciences. Fluorescent proteins such as GFP and DsRed fused to the protein of interest (POI) allow expression analysis and in vivo protein localization. Their application however, is limited due to the large molecular weight of those fusion proteins. Furthermore, the associated molecular biology is tedious and time-consuming. Small fluorophores, covalently attached to the POI, may help to overcome this problem. Fluorescent labeling of the thiol group of cysteines is preferred for investigating structure, function and interactions of the POI. (Please note: Jena Bioscience offers a ready-to-use kit for labeling of cysteine residues with high-quality small fluorophores (Cat.# FP-202) for application in protein activity and functional studies). The most common labeling method for proteins however, is amine modification. Amine-reactive fluorophores such as NHS-esters readily react with primary amino groups present at the N-terminus[1] as well as in lysine side chains, resulting in a stable covalent bond. This Jena Bioscience Protein Labeling Kit is designed for labeling the lysines of a POI with a small fluorophore resulting in a fluorescent protein-fluorophore conjugate. It contains all reagents required for performing 10 separate labeling reactions of 1 mg of POI.