distance dependence of charge carrier injection into dna
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Distance dependence of charge carrier injection into DNA
Kinetic scheme for hole injection, hopping and trapping in DNA
E
(X+)*
Hole Trap
G G
A A
C CT T
G
A
CT
X+
N
HN
OOP
H
O
OO-
Cl
MeO
X+-Labeled DNA duplexes
3‘ 5‘
A X+
T A
T A
GC
T A
A
T A
T A
T A
X+
GC
3‘ 5‘
A
T A
T A
X+
T A
GC
3‘ 5‘
XAG
X+AG
1(X+)*AG
0
0.5
1.0
Wavelength [nm]
Ab
sorb
ance
/Flu
ores
cen
ce
[a.u
.]
400 600500
Structural Characterization
• Melting Points• CD Spectra• NMR Structure
transition dipole moments of ACMA vs. duplex axis: ~70-75° consistent with time-resolved fluorescence polarisation (65-90°)
H6,H8 H1‘
H2‘‘
H2‘
MeasuredCalculated
Restraints :• NOEs (136 intra DNA + 7 inter ACMA-DNA) 0 violations (>0,2 Å)• Anisotropy of chemical shifts
QF-ACMA-NMR Struktur 1 03-10-21.ppt
NMR structure of 5‘ GCGTAAX+AATGCG duplex
Griesinger/Neubauer 2003
Kinetics of photo-induced guanine oxidation via (X+)*
-1 0 10 100 1000
-1,0
-0,5
0,0
0,5
1,0
455 nm Pump / 500 nm Probe
X+(AT) X+G X+AG
A (
a.u.
)
Time (ps)
X+AT CGC TAT TAT TAX+ ATT TAT CGC-3’
X+GA GCG TTA TAA GX+A TAA TAT GCG-3’
X+AGA GCG TTA TAG AX+A TAA TAT GCG-3’
Duplex ES (ns) CS (ns) CR (ns)X+G 0.003 0.003 0.030X+AG 6.9 11.2 ----X+ AT 18.0 ---- ----
kG / kAG ~ 4000“” ~ 2.4 Å-1
Factors controlling nonadiabatic charge transfer
Marcus formula:
classical nuclear dynamics
ET rate k determined by distance
dependant 3 terms
– effective electronic coupling HDA
– free energy change G
– reorganization energy
2
22 1exp
4 ( )4 ( )DA
G R Rk H R
R kTR kT
X+Z 5’-GCG TTA TAA ZX+A TAA TAT GCGX+AZ 5’-GCG TTA TAZ AX+A TAA TAT GCGX+AAZ 5’-GCG TTA AZA AX+A TAA TAT GCG
NH
O
PO O
O
O
PO O
O NH
Cl
H3CO
+
[
[
X+ =
Distance dependent activation energy of hole transfer rates in DNA duplex
Temperature Range: 245-305 K
HF-Analysis of Ea and k-03-10-21.ppt
How to analyze activation energies and rates
TkE
expT
Ak
B
a21
2
/)λ(V
A
weak contribution
Duplex Ea [eV] kFET [s-1]
(T=285 K) [s-1]
X+Z < 0.015 2.0 1012 6.2 1013
X+AZ 0.09 ± 0.01 9.3 1010 6.3 1013
X+AAZ 0.20 ± 0.02 4.6 107 2.8 1012
X+G 0.08 ± 0.04 2.0 1011 9.1 1013
X+AG 0.20 ± 0.04 6.5 107 4.0 1012
4
GE
2
a
Tk/EFET
BaeTkA
Distance dependence of reorganisation energy
λ
λGEa
4
2
Duplex Ea [eV] FET [eV]
X+G 0.08 ± 0.04 0.6 ± 0.1
X+AG 0.20 ± 0.04 1.0 ± 0.2
X+Z < 0.015 0.6 ± 0.1
X+AZ 0.09 ± 0.01 1.1 ± 0.1
X+AAZ 0.20 ± 0.02 1.4 ± 0.1
+ + ½ + ½
Small D/A distance&Smaller
Large D/A distance&Larger
Initial states Transition states
+ + ½ + ½
Reorganisation energy for the simple case of a self-exchange reaction
(G=0)
sopDAs εεRrr
)e(λ111
2
1
2
1
21
2
Distance dependence of the medium reorganization energy
stopDAADs Rrr
e
11121
21
)( 2
Marcus Two-Sphere-Model:
rD rA 4.5 Å
Optimization of charge transport energetics
Minimization of medium reorganization energy
• Short D/A distances
• Nonpolar environment
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