The use of biotin for non-radioactive labeling of proteins and nucleic acids has now become an increasingly popular technique in life science research

G-Biosciences' HOOK™-Biotin-Pentylamine, HOOK™-Biotin-PEG₂-Amine, and its long chain form, HOOK™-Biotin-PEG₃-Amine, are carboxyl reactive biotinylation reagents. These agents contain terminal amines and react with carboxyl groups found at the carboxyl termini, aspartate, and glutamate side chains. The reaction is mediated by a water-soluble carbodiimide (EDC). The carbodiimide activates the carboxyl group and reacts with the amines (-NH₂) on the biotinylation agent to form an amide bond. This reaction is rapid and takes just a few minutes to complete. Under these conditions, hydrazide-derivatives of biotin reagents may also react with the carboxyls.

G-Biosciences' HOOK™ Carboxyl Reactive Biotin Reagents are each available as the reagent alone or as part of a biotin labeling kit. The labeling kits are designed and supplied with all the necessary reagents, equipment and instructions necessary for optimal reaction conditions, efficient labeling, removal of unbound biotin, and quantification of biotin labeling, for the conjugation of biotin to protein carboxyl groups.

Each kit is supplied with 25 milligrams of the specific HOOK™ Carboxyl Reactive Biotin Reagent, a specific Optimizer Buffer™ for enhanced conjugation, Spin-OUT™ columns for rapid (less than 10 minute) purification of labeled protein, and reagents to determine the amount of biotinylation. The kits are each designed for the coupling of 1 to 10 milligrams protein in 1 milliliter buffer, suitable for 10 couplings.

Several factors must be considered when coupling a biotin reagent to a protein to ensure a successful reaction. The primary consideration is the selection of the biotinylation reagent itself. G-Biosciences offers a wide range of biotin reagents with variations in their reactive groups, spacer arm lengths, solubility, membrane permeability and reversibility. All of these factors must be considered and are dependent on your protein/peptide.