Catalytic molecular beacons

We have constructed catalytic molecular beacons from a hammer-head-type deo xyribozyme by a modular design. The deoxyribozyme was engineered to contain a molecular beacon stem-loop module that, when closed, inhibits the deoxyr ibozyme module and is complementary to a target oligonucleotide. Binding of target oligonucleotides opens the beacon stem-loop and allosterically acti vates the deoxyribozyme module, which amplifies the recognition event throu gh cleavage of a doubly labeled fluorescent substrate. The customized modul ar design of catalytic molecular beacons allows for any two single-stranded oligonucleotide sequences to be distinguished in homogenous solution in a single step. Our constructs demonstrate that antisense conformational trigg ers based on molecular beacons can be used to initiate catalytic events. Th e selectivity of the system is sufficient for analytical applications and h as potential for the construction of deoxyribozyme-based drug deliver tools specifically activated in cells containing somatic mutations.