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Coadsorption of Complementary and Noncomplementary Bases on Au(111)

Coadsorption of Complementary and Noncomplementary Bases on Au(111) A. P. M. Camargo, C. Donner Free University Berlin Institute of Physical and Theoretical Chemistry. Nonstandard base pair Mutagenicity Cancer Therapy  How does it work? - Mutagenicity: one DNA

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Coadsorption of Complementary and Noncomplementary Bases on Au(111)

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  1. Coadsorption of Complementary and Noncomplementary Bases on Au(111) A. P. M. Camargo, C. Donner Free University Berlin Institute of Physical and Theoretical Chemistry

  2. Nonstandard base pair Mutagenicity Cancer Therapy  How does it work? -Mutagenicity: one DNA base (thymine) is replaced by a nonstandard base (BrU) -Cancer Therapy: substitution of one base by BrU at DNA leads to a greater sensitivity to ionising radiation Nitrogened bases Problem Phosphate group Deoxyribose * * M. Orozco et al., J. Phys.Chem. B, 1998,102, 5228

  3. Is it possible • to obtain interaction of standard /nonstandard base pairs? • to distinguish between the different interactions? Idea Thymine - undergoes a phase transition at Au(111) - orientation of molecules depends on the potential Adsorption behaviour of DNA base at electrode 40 Thymine 20mM -Complementary base pair: Adenine / Thymine -Noncomplementary base pairs:Adenine / Bromouracil Guanine / Bromouracil Investigation 20 * -2 Acm m 0 j / physisorbed phase chemisorbed phase -20 -40 -0.9 -0.6 -0.3 0.0 0.3 0.6 + E / V vs. Ag/Ag *(a) W.Haiss et al., J. Electroanal. Chem.,1998, 454, 107; (b) B. Roelfs, H. Baumgärtel, Ber. Bunsenges Phy. Chem.,1995, 99, 677

  4. Cell - Au(111)  Electrodes - Ag/Ag+ - gold wire  Supporting Electrolyte: 0.1M NaClO4 / + DNA bases, BrU  pH=2 Experimental Part

  5. * * Complementary Bases *Y.J.Xiao, Y.F.Chen, Spectrochemica Acta, Part A, 1999, 55, 1209.

  6. H+ Adenine-Dimers Coadsorption Behaviour

  7. * Noncomplementary Bases chemisorbed phase physisorbed phase

  8. *F. Nart., Surface Science, 480, 2001, L383 Coadsorption Behaviour

  9. * Noncomplementary Bases

  10. Coadsorption Behaviour

  11. -We found attractive interactions between A-T complementary base pair1, whereby adenine was chemisorbed at the thymine physisorbed phase • - For the noncomplementary base pairs BrU-A and BrU-G we did not find any indication for attractive interactions • -The phase transition in a physisorbed condensed film for noncomplementary pairs vanishes if coadsorption takes place, it means that the interaction between them is weaker than between the bases alone (according to A-T on Hg electrodes2) • 1- A.P.M. Camargo, H. Baumgärtel, C. Donner, Phys. Chem. Chem. Phys., 5, 2003, 1657 • 2- S. Kirste, C. Donner, Phys. Chem. Chem. Phys., 3, 2001, 4384 Conclusions

  12. Adenine Guanine Uracil Tymine Cytosine

  13. Tymine Adenine

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