Thermodynamics and Kinetics of Unfolding of Antiparallel G-Quadruplexes in Anti-Thrombin Aptamers.

The process of unfolding of G-quadruplex structure in the RE31 DNA-aptamer and in its complex with thrombin under the action of the fluorescently labeled complementary oligonucleotides of varying length with formation of double-helix structures has been studied. It has been suggested that G-quadruplex unfolding involves formation of an intermediate complex with an oligonucleotide. Thermodynamic parameters and kinetics of unfolding of the free aptamer and its complex with thrombin differ.

DNA Aptamers to Thrombin Exosite I. Structure-Function Relationships and Antithrombotic Effects.

DNA aptamers (oligonucleotides) interacting with thrombin exosite I contain G-quadruplex, two T-T, and one T-G-T loops in their structure. They prevent exosite I binding with fibrinogen and thrombin receptors on platelet surface, thereby suppressing thrombin-stimulated formation of fibrin from fibrinogen and platelet aggregation. Earlier, we synthesized original antithrombin aptamer RE31 (5'-GTGACGTAGGTTGGTGTGGTTGGGGCGTCAC-3') that contained (in addition to G-quadruplex) a hinge region connected to six pairs of complementary bases (duplex region).

[Study of the quantity of interleukin-6 by SDS-PAAG electrophoresis and immuno-enzyme analysis in mixed saliva after rinsing the oral cavity with oligonucleotide specific.].

The selective properties of a solution of oligonucleotide specific to IL-6 on the concentration of IL-6 in mixed saliva of patients with oral inflammatory processes were studied using SDS-PAGE by electrophoresis and enzyme immunoassay. The application of these methods showed that in the mixed saliva of patients after rinsing with a solution of an oligonucleotide specific for IL-6, the amount of IL-6 decreases. The ELISA Kit and 20% SDS-PAGE showed the highest sensitivity to determine the concentration of IL-6 in saliva, which should be considered in clinical laboratory practice.

Four steps for revealing and adjusting the 3D structure of aptamers in solution by small-angle X-ray scattering and computer simulation.

Nucleic acid (NA) aptamers bind to their targets with high affinity and selectivity. The three-dimensional (3D) structures of aptamers play a major role in these non-covalent interactions. Here, we use a four-step approach to determine a true 3D structure of aptamers in solution using small-angle X-ray scattering (SAXS) and molecular structure restoration (MSR).

Several structural motifs cooperate in determining the highly effective anti-thrombin activity of NU172 aptamer.

Despite aptamers are very promising alternative to antibodies, very few of them are under clinical trials or are used as drugs. Among them, NU172 is currently in Phase II as anticoagulant in heart disease treatments. It inhibits thrombin activity much more effectively than TBA, the best-known thrombin binding aptamer.