Quantum Theory of DNA

1
Quantum Theory of DNAAn Approach to Electron
Transfer in DNA

• H. Sugawara, 2005
• Work being done with H. Ikemura

1. Introduction

motivation ? Ikemura Conjecture Ikemura
Conjecture Electron transfer in DNA is playing
an important role in the information exchanges
among the various sections of DNA.
Example
2
(No Transcript)
3
Standard technique in particle theory and in
condensed matter theory but maybe not in quantum
chemistry.Consider electrons interacting with
the centers of potential (ions) located at Ri
2. Field Theory Technique
electromagnetic interactions (gauge principle)
4
? electron-phonon interactions
5
3. Hartree approximations
Include in V(x) ? Veff
6
(No Transcript)
7
Further approximations
only nearest neighbors
Then we have
Special case of H ? Su-Schrieffer-Heegger
Hamiltonian b, g constant , j longitudinal
?
8
can also be defined in a similar way
Then we replace
9
Here
was utilized
10
RNA transcription
DNA replication
11
? Consider classical and longitudinal oscillation
localized (tightly bound) wave function
? general case with classical oscillation
12
WKB solution
13
? The localization depends on the sign of
and of
? Back to the descrete description
applications

1. Luminescence quenching
2. Electric current
3. Absorption of light

14
Luminescence quenching
Ru-ligand
luminescence
mixed system
absorption
Rh
provides electrons ? quenching
quenching occurs by a hole propagation inside
DNA
Note 1. Prokariote closed string 2.
Eukariote open string end telomere
with certain protein
15
(No Transcript)
16
Probability of quenching
DNA electrons transfer to (from) metals
17
Density at Lh
18
Electric current in DNA
19
(No Transcript)
20
(No Transcript)
21
Coupling to backbone electrons
add
This may be important in explaining the current?
22
There must be an overlap
23
(1) Ef is within the band
(2) Ef is outside of the band
semiconductor-like
24
Optical absorption (Sarukuras proposal)
excited band ground band
em interaction
25
absorption rate
26
Conclusion

1. Three dimensional string action for DNA is
   derived
2. Approximate p-electron wave functions are derived
3. Applications to luminescence quenching, electric
   current through DNA and optical absorption are
   formulated

remaining problems

1. Comparison with experiments
2. Bound states with proteins
3. Quantized phonon
4. Improvement of approximations