Cleavage of RNA bulge loops by artificial RNases

Sensitivity of phosphodiester bonds in RNA bulge loops to cleavage by short cationic peptides and compounds based on 1,4-diazabicyclo[2.2.2]octane and its conjugates with imidazole was studied. Bulge loops containing from one to seven nucleotides were formed in RNA upon its hybridization with partially complementary oligodeoxyribonucleotides. The efficiency of RNA cleavage depends on the length of a bulge loop, the position of the cleaved phosphodiester bond in the loop, and the nature of the RNA-binding fragment of chemical ribonuclease (1,4-diazabicyclo[2.2.2]octane or a cationic peptide). In the absence of Mg²⁺ ions, the phosphodiester bond in the CA motif located in the apical position in 4-, 6-, or 7-membered loops is cleaved with the highest efficiency. In the presence of magnesium ions, the selectivity of RNA cleavage within bulge loops is substantially enhanced. In the case of 1,4-diazabicyclo[2.2.2]octane-based compounds, RNA is subjected to cleavage predominantly at the bonds in 4-, 6-, and 7-membered loops, whereas cleavage of other bonds is greatly suppressed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1236–1246, July, 2006.     

Acridine-based macrocycles as potential probes for studies of the structures of nucleic acids

The possibility of the use of bis- and tris-acridine macrocycles as photoactivated reagents, which are sensitive to the DNA and RNA secondary structures, was examined. The bis- and tris-acridine macrocycles can induce photomodification (in the case of DNA) and photocleavage (in the case of RNA). Both processes occur predominantly at the purine residues located in loops or at the junction of the RNA and DNA hairpins.     

Proton-pion and two- pion correlations in eA interactions

We report here the results on studying of proton-pion and two-pion correlations in eA interactions at 5 GeV. Kinematic correlations were studied as a function of the two-particle opening angle, their momenta and proton multiplicity. The universal properties of correlation functions were found with respect to different particle species. Interferometry method was used to determine the size of the interaction region.     

Simultaneous measurement of static and kinetic friction of ZnO nanowires in situ with a scanning electron microscope

A novel method for in situ measurement of the static and kinetic friction is developed and demonstrated for zinc oxide nanowires (NWs) on oxidised silicon wafers. The experiments are performed inside a scanning electron microscope (SEM) equipped with a nanomanipulator with an atomic force microscope tip as a probe. NWs are pushed by the tip from one end until complete displacement is achieved, while NW bending is monitored by the SEM. The elastic bending profile of a NW during the manipulation process is used to calculate the static and kinetic friction forces.