Improved nucleic acid triggered probe activation through the use of a 5-thiomethyluracil peptide nucleic acid building block.

To improve the efficiency of a nucleic acid triggered probe activation (NATPA) system a 5-thiomethyluracil peptide nucleic acid (PNA) building block has been synthesized. Attachment of imidazole and a coumarin ester to uracils at the ends of two PNAs resulted in a 550 000-fold acceleration of DNA-triggered coumarin release relative to imidazole and a 6-fold increase in k(cat) relative to a system which had these groups attached to the amino and carboxy ends of PNAs. [structure: see text]