How does an antibody labeling kit work?

An antibody labeling kit uses an amine-reactive fluorophore such as Pacific Blue, Alexa Fluor, or Pacific Orange to covalently attach the label or tag (e.g. fluorescent or biotin label) to the target antibody. The covalent bond between the label and protein is highly stable after it is formed. Standard antibody labeling kits are produced specifically for labeling 100 micrograms of antibody per reaction. One must adjust protein concentration to approximately 1 mg/mL in the given buffer and then add it to a tube of amine-reactive dye. Stabilizing proteins must be removed before the labeling reaction. Purification is carried out on a size exclusion spin column created for more than 40 kDa proteins. The labeling and purification process together can be completed in less than 90 minutes.