The amine group is the most common target for modifying protein molecules because it is abundant in the majority of proteins either due to the presence of lysine bearing amino side chain functionality or the N-terminal-amine. Amine-reactive biotinylation reagents can be divided into two groups based on water solubility: NHS-esters and sulfo-NHS-esters.

NHS-esters of biotin are water-insoluble and membrane-permeable because they do not possess a charged group. They may be used for biotinylating internal as well as external cellular components.

Sulfo-NHS-esters are water soluble and useful for applications that cannot tolerate organic solvents. Sulfo-NHS-esters of biotin are recommended for use as cell surface biotinylation reagents. Because of the charged sulfonate group, these compounds do not penetrate the plasma membrane, thus sulfo-NHS-esters biotinylation is restricted to the cell surface.

Choose the best amine-reactive biotinylation kit for your experiment

Kit categories Product Product features Spacer arm (Å) Water  soluble? Cleavable?
NHS-PEG4-Biotin and Biotinylation Kits PEG4-Biotin transfer and label amines, and maximize the solubility of antibodies and other proteins 29 Yes  No 
Sulfo-NHS-Biotin and Biotinylation Kits Complete kit with a fast  and efficient procedure for labeling a protein and determining how much biotin has been attached 13.5  Yes No 
Sulfo-NHS-LC-Biotin and Biotinylation Kits Complete kit with an optimized procedure for labeling a protein and determining how much biotin has been attached 22.4  Yes No 
Sulfo-NHS-SS-Biotin and Biotinylation Kits

Cleavable biotinylation reagent allows for later removal of the biotin label  

24.3 Yes  Yes 
NHS-PEG Solid Phase Biotinylation Kits A column-based approach to antibody biotinylation and clean-up N/A N/A N/A