Prevents carry-over contamination
Contamination PCRs with trace amounts of PCR products, called carry-over contamination, yields false positive results. Carry-over contamination from previous PCR can be a significant problem, due to the abundance of PCR products.
Carry-over contamination can be prevented by incorporating dUTP in all PCR products and treating all subsequent fully preassembled starting reactions with uracil DNA glycosylase (UDG), followed by thermal inactivation of UDG. UDG cleaves the uracil base from the phosphodiester backbone of uracil-containing DNA, but has no effect on natural (i.e., thymine-containing) DNA. The resulting apyrimidinic sites block replication by DNA polymerases, and are very labile to acid/base hydrolysis. Because UDG does not react with dUTP, and is also inactivated by heat denaturation prior to the actual PCR, carry-over contamination of PCRs can be controlled effectively if the contaminants contain uracils in place of or in addition to thymines.