Nucleic acid catalysts with endonuclease activity

A nucleic acid molecule with endonuclease activity to cleave a substrate RNA having the formula V:

• wherein, X and Y are independent oligonucleotides comprising 3 or more nucleotides;
• L is a linker which may be present or absent, wherein said linker, when present, is independently or in combination a nucleotide linker, or a non-nucleotide linker;
• Z is independently a nucleotide which is complementary to a nucleotide in the substrate RNA and C, G, A, and U represent cytidine, guanosine, adenosine, and uridine nucleotides, respectively, wherein each of said X and Y oligonucleotides independently comprises a sequence complementary to a portion of the substrate RNA.