背景介绍 Biotin-labeling is commonly used for non-radioactive labeling and purification of proteins and other target molecules. Biotin labeling takes advantage of the exceptionally strong interaction between biotin (vitamin H) and either avidin or streptavidin. The affinity of biotin to avidin or streptavidin is one of the strongest known non-covalent interactions of a protein and ligand, exhibiting a dissociation constant (Kd) around 10-15. BirA protein ligase covalently adds biotin to biotin-acceptor peptides containing an AviTag™ sequence in a highly efficient and specific ATP-dependent reaction. 产品介绍 BirA-transformed Competent E. coli cells are supplied as 10 x 50 µl vials. Strain BL21, a chemically competent E. coli B strain, contains an IPTG-inducible BirA expression plasmid and constitutively-expressed streptomycin/spectinomycin resistance gene. These cells are compatible with most cloning vectors and are suitable for expression and biotinylation of recombinant proteins using AviTag™ technology.