DNA fragmentation represents a characteristic hallmark of apoptosis. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) is an established method for detecting DNA fragments.
TACS XL® kits embody a novel approach for the detection of apoptosis. This assay is based on incorporation of biotinylated nucleotides conjugated to bromodeoxyuridine (BrdU) at the 3' OH ends of the DNA fragments that form during apoptosis. This detection system utilizes a biotin conjugated anti-BrdU antibody and streptavidin-horseradish peroxidase. TACS XL kits are available with colorimetric substrates diaminobenzidine (DAB) or TACS Blue Label.