Abstract: This invention is directed to a composition for catalyzed oligonucleotide cleavage comprising a synthetic non-naturally occurring oligonucleotide compound. The compound comprises nucleotides whose sequence defines a conserved group II intron catalytic region and nucleotides whose sequence is capable of hybridizing with a predetermined oligonucleotide target sequence to be cleaved, such target sequence not being present within the compound. The composition also includes an appropriate oligonucleotide co-factor. Preferably, the conserved group II intron catalytic region is a group II intron domain I catalytic region. In one embodiment the conserved group II intron domain I catalytic region may further comprise a conserved portion of a group II intron domain II, a group II intron domain III, a group II intron domain IV, a group II intron domain V, or a group II intron domain VI. The invention is also directed to methods of treatment and methods of use of such compounds.