Locked nucleoside analogues expand the potential of DNAzymes to cleave structured RNA targets.

Background: DNAzymes cleave at predetermined sequences within RNA. A prerequisite for cleavage is that the DNAzyme can gain access to its target, and thus the DNAzyme must be capable of unfolding higher-order structures that are present in the RNA substrate. However, in many cases the RNA target sequence is hidden in a region that is too tightly structured to be accessed under physiological conditions by DNAzymes.

LNA and alpha-L-LNA: towards therapeutic applications.

LNA and alpha-L-LNA are promising candidates for the development of efficient oligonucleotide-based therapeutic agents. Here, we report dose-dependent inhibition of HIV-1 Tat-dependent trans activation by a 12-mer chimeric alpha-L-LNA/DNA oligomer. This oligomer exhibits a dose-dependency similar to that of the corresponding 12-mer chimeric LNA/2'-O-Me-RNA oligomer.

LNAzymes: incorporation of LNA-type monomers into DNAzymes markedly increases RNA cleavage.

Incorporation of two alpha-L-LNA/LNA nucleotides into each of the two binding arms of a "10-23" DNAzyme has been accomplished and the RNA cleavage with these novel LNAzymes studied. In comparison with the unmodified DNAzyme, the LNAzymes show significantly improved cleavage of the phosphodiester backbone at the target nucleotide in a small RNA substrate (58n RNA) under single-turnover conditions. The LNAzymes show efficient multiple turnover.