FIG. 2.

(a) PCR with a complementary MGB probe. During the extension phase with primers, the DNA polymerase cleaves the reporter dye from the probe, and the dye emits its characteristic fluorescence. When a PNA added to the reaction mixture is noncomplementary to the target sequence, it does not affect amplification with a complementary MGB probe. NFQ, nonfluorescent quencher. (b) PCR with a complementary PNA. The mismatch of an MGB probe noncomplementary to the target sequence is blocked by the PNA, which is preferentially bound at a higher melting temperature than the MGB probe.