Ribonuclease activity of the peptides with alternating arginine and leucine residues conjugated to tetrathymidilate.

RNA cleaving conjugates have been prepared by attachment of oligodeoxyribonucleotide TTTT to peptides containing arginine, leucine, proline and serine residues. The highest activity was displayed by the conjugates containing peptides with alternating arginine and leucine residues (LR)4G-amide. Ribonuclease activity of the conjugates pep-T4 decreases in the order T4-(LR)4G > T4-(LR)2G > T4-(LLRR)2G > T4-(LR)2PRLRG > S2R3-Hmda-T4 > or = R5 double dagger (LR)3. According to CD spectra, the free peptide (LR)4G-amide in water solution at neutral pH and physiological ionic strength has no pronounced secondary structure whereas conjugated to oligonucleotide it acquires a folding similar to alpha-helix.