Lipid-assisted Synthesis of RNA-like Polymers from Mononucleotides

A fundamental problem in research on the origin of life is the process by which polymers capable of catalysis and replication were produced on the early Earth. Here we show that RNA-like polymers can be synthesized non-enzymatically from mononucleotides in lipid environments. The RNA-like polymers were initially identified by nanopore analysis, a technique with single molecule sensitivity. To our knowledge, this is the first such application of a nanopore instrument to detect RNA synthesis under simulated prebiotic conditions. The synthesis of the RNA-like polymers was confirmed by standard methods of enzymatic end labeling followed by gel electrophoresis. Chemical activation of the mononucleotides is not required. Instead, synthesis of phosphodiester bonds is driven by the chemical potential of fluctuating anhydrous and hydrated conditions, with heat providing activation energy during dehydration. In the final hydration step, the RNA-like polymer is encapsulated within lipid vesicles. This process provides a laboratory model of an early stage of evolution toward an RNA World.     

Mechanism of oligonucleotide hybridization with the 3′-terminal region of the yeast tRNAPhe

Interaction of yeast phenylalanine tRNA with oligonucleotides complementary to its 3′-terminal nucleotide sequence was thoroughly studied. Using the gel retardation technique, thermodynamic and kinetic parameters of the tRNA complexation in physiological conditions were determined. Analysis of dependences of the complex formation on the oligonucleotide concentration and incubation time showed that this process proceeds in two stages. At the first stage, a metastable complex of the oligonucleotide with the open, single-stranded sequence ACCA at the 3′ end of tRNA rapidly forms. The second stage involves a slow intramolecular rearrangement of the resulting metastable complex into a full-sized heteroduplex accompanied by the tRNA^Phe unfolding. The data gained suggest that the RNA unfolding stage is limiting in the interaction of oligonucleotides with natural RNAs. Principles of selection of optimal hybridization probes and antisense oligonucleotides are discussed.     

Synthesis and Characterization of Artificial Ribonucleases

Abstract

RNA cleaving molecules were synthesized by conjugating components of ribonucleases A and T1 catalytic centers (imidazole, aliphatic amino and/or carboxy residues) to intercalating and cationic structures. The artificial ribonucleases were shown cleave RNA at Py-Pu sites in single-stranded regions.     

Modern methods of prostate cancer diagnostics

The review highlights analytic capacities of immunochemical and molecular-genetic methods used in the non-invasive test for prostate cancer and monitoring of efficacy of anticancer therapy. The perspectives of their applications in clinical practice also have been evaluated.     

Ethidium and azidoethidium oligonucleotide derivatives: Synthesis,complementary complex formation and sequence-specific photomodification of the single-stranded and double-stranded target oligo- and polynucleotides

Oligodeoxyribonucleotide derivatives containing ethidium or azidoethidium residues attached to 3′ and/or 5′ end were prepared. These derivatives formed tight specific complexes with complementary oligodeoxyribonucleotides where each attached ethidium residue led to an increase of complex T_m by 20–30°C. Tandem complexes of two oligodeoxyribonucleotides containing ethidium residues with an oligodeoxyribonucleotide having two adjacent complementary sequences for these Oligonucleotide were investigated. Photoinduced reactions of a number of ethidium and azidoethidium oligodeoxyribonucleotide derivatives with target complementary single-stranded and double-stranded oligo- and polydeoxyribonucleotides were investigated. The irradiation led to direct photocleavage of the target oligo- or polynucleotide, to formation of hidden (piperidine cleavable) modifications of the target of formation of covalent adducts between ethidium oligodeoxyribonucleotide derivative and the target. In a number of experiments, azidoethidium dyes were demonstrated to be considerably stronger photosensitizers than ethidium ones. Depending on the nature of the target (single- or double-stranded DNA) and on the irradiation conditions, the total damages to the target oligo- or polydeoxyribonucleotides ranged from 10–70% (for ethidium dyes) to 30–80% (for azidoethidium dyes).