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Distance dependence of charge carrier injection into DNA

Distance dependence of charge carrier injection into DNA. Kinetic scheme for hole injection, hopping and trapping in DNA. E. C. T. T. C. C. T. A. A. A. (X + )*. G. G. G. Hole Trap. X +. X + -Labeled DNA duplexes. 5‘. 5‘. 5‘. 3‘. 3‘. 3‘. T. A. T. A. C. G. G. C. C.

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Distance dependence of charge carrier injection into DNA

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  1. Distance dependence of charge carrier injection into DNA

  2. Kinetic scheme for hole injection, hopping and trapping in DNA E C T T C C T A A A (X+)* G G G Hole Trap X+

  3. X+-Labeled DNA duplexes 5‘ 5‘ 5‘ 3‘ 3‘ 3‘ T A T A C G G C C G Absorbance /Fluorescence [a.u.] X+ X+ A A T A A T T A 400 500 600 T A Wavelength [nm] T A A X+ T A T A 1(X+)*AG 0 0.5 1.0 X·AG·+ X+AG • Structural Characterization • Melting Points • CD Spectra • NMR Structure

  4. NMR structure of 5‘ GCGTAAX+AATGCG duplex H6,H8 H1‘ Measured Calculated H2‘‘ H2‘ Restraints : • NOEs (136 intra DNA + 7 inter ACMA-DNA) 0 violations (>0,2 Å) • Anisotropy of chemical shifts transition dipole moments of ACMA vs. duplex axis: ~70-75° consistent with time-resolved fluorescence polarisation (65-90°) Griesinger/Neubauer 2003 QF-ACMA-NMR Struktur 1 03-10-21.ppt

  5. 455 nm Pump / 500 nm Probe 1,0 X+(AT) X+G 0,5 X+AG A (a.u.) 0,0 D -0,5 -1,0 -1 0 10 100 1000 Time (ps) Kinetics of photo-induced guanine oxidation via (X+)* X+AT CGC TAT TAT TAX+ATT TAT CGC-3’ X+GA GCG TTA TAA GX+A TAA TAT GCG-3’ X+AGA GCG TTATAG AX+A TAA TAT GCG-3’ DuplextES (ns)tCS(ns)tCR(ns) X+G 0.003 0.003 0.030 X+AG 6.9 11.2 ---- X+ AT 18.0 ---- ---- kG / kAG ~ 4000 “b” ~ 2.4 Å-1

  6. Marcus formula: classical nuclear dynamics ET rate k determined by distance dependant 3 terms effective electronic couplingHDA free energy changeG reorganization energy Factors controlling nonadiabatic charge transfer

  7. Distance dependent activation energy of hole transfer rates in DNA duplex [ + X+ = [ X+Z5’-GCG TTA TAA ZX+A TAA TAT GCG X+AZ5’-GCG TTA TAZ AX+A TAA TAT GCG X+AAZ5’-GCG TTA AZA AX+A TAA TAT GCG Temperature Range: 245-305 K

  8. How to analyze activation energies and rates weak contribution HF-Analysis of Ea and k-03-10-21.ppt

  9. Distance dependence of reorganisation energy

  10. Reorganisation energy for the simple case of a self-exchange reaction (G=0) Small D/A distance & Smaller  + ½ + ½ + + ½ + ½ + Large D/A distance & Larger  Transition states Initial states

  11. Distance dependence of the medium reorganization energy Marcus Two-Sphere-Model: rDrA 4.5 Å

  12. Optimization of charge transport energetics • Minimization of medium reorganization energy • Short • D/A distances • Nonpolar • environment

  13. On the distance dependence of charge transfer in DNA Who did the work? M.E. Michel-Beyerle Group: Design of Oligonucleotides and fs pump-probe spectroscopy Stephan Hess (Thesis 2002) & M. Götz (Thesis 2002) William B. Davis (now at Washington State at Pullman) Till von Feilitzsch & Gagik Gurzadyan at present Nanosecond pump-probe spectroscopy Isabella. Naydenova, Reinhard Haselsberger & Alex Ogrodnik Collaborations Fs Broadband Absorption spectrocopy N. P. Ernsting , S. A. Kovalenko & J. L. Pérez Lustres (HU Berlin) NMR Structure C. Griesinger & H. Neubauer (MPI Göttingen) Thermal Injection & Charge Transport B. Giese (U. Basel) Quantum Chemical Computations & MD Simulations N. Rösch & A. Voityuk (TU München) Modelling of Charge Transfer & Transport Dynamics M. Bixon & J. Jortner (Tel Aviv U.) M. D. Newton (Brookhaven) Funding VW-Stiftung DFG SFB 377 EU 5th & 6th Frame Program

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