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Sokolov P.A.,Saint Petersberg State University | Bazlov N.V.,Saint Petersberg State University | Puchkova A.O.,Saint Petersberg State University | Vyvenko O.F.,Saint Petersberg State University | Kasyanenko N.A.,Saint Petersberg State University
Protection of Metals and Physical Chemistry of Surfaces | Year: 2011

DNA molecules immobilization on n-type single silicon was investigated. Electronic states were studied by measuring voltage-ampere characteristics (VAC) of Au-(n-Si) contacts with DNA molecules on the interface. It is showed that strong DNA fixation is observed in the presence of magnesium ions in solution. Molecules conformation on the surface is determined by the degree of the substrate hydrophobicity. Devel- oped method of DNA immobilization allows to create model systems with the molecules in the form of molecular mesh or ropes depending on irradiation intensity. Formed on the silicon surface molecular struc- tures have different effect on the electrical properties of Au-DNA-(n-Si) contacts. Presence of molecular mesh on the Schottky diode interface makes its VAC similar to ideal diode. The ropes lead to electronic state density increasing. © Pleiades Publishing, Ltd., 2011.

Tulub A.A.,The Interdisciplinary Center | Tulub A.A.,Saint Petersberg State University | Stefanov V.E.,The Interdisciplinary Center | Stefanov V.E.,Saint Petersberg State University
Physical Biology | Year: 2015

The DFT:B3LYP (6-31G∗∗ basis set) method, including the hyperfine and spin-orbit couplings (HFC and SOC, respectively), is used to study the separation of two complementary trinucleotide sequences, (dC-dG-dA)-(dG-dC-dT), upon the action of two Mg(2+) cofactors (a simplified model). The computations reveal a crossing of the singlet (S) potential energy surface by the triplet (T) surface at two distinct points. Within the crossing region the T curve lies below the S curve. Adhering to the concept of the minimal energy path, one can assume that the T path is more favorable compared to that of the S path. The T path is not simple; it consists of two, T+ and T-, curves initially separated by the HFC and SOC. On reaching the second crossing point, both curves merge into the T0 state, which facilitates the T → S transfer. Totally, the process of the two trinucleotide separation (the first step of transcription) appears as the S → T → S symmetry conversion. © 2015 IOP Publishing Ltd.

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