Biotin-16-dUTP can be enzymatically incorporated into DNA via nick translation, random priming, or 3' end terminal labeling. The terminal deoxynucleotidyl transferase (TdT)-mediated biotin-dUTP nick end-labeling (TUNEL) method has been commonly used for apoptosis studies. The number '16' is the number of atoms in the linker between biotin and dUTP. Biotium also offers biotin-11-dUTP and biotin-20-dUTP. The length of the linker affects the incorporation efficiency of the biotin-dUTP probe into DNA using DNA polymerases, and it also affects biotividin or biotin/streptavidin. In general, the shorter the linker, the more efficiently the biotin-dUTP is incorporated into DNA by DNA polymerases. On the other hand, a longer linker should facilitate interaction between biotin and avidin or streptavidin.    1 mM solution in pH 7.5 Tris-HCl buffer  Store at -20°C  C32H48N7O18P3Sli4  MW: 971.5    Biotin-16-dUTP is also available as a lyophilized solid.