Contributions of the distance-dependent reorganization energy and proton-transfer to the hole-transfer process in DNA.
A kinetic study of the single-step hole transfer in DNA was performed by measuring time-resolved transient absorption. DNA molecules with various sequences were designed and conjugated with naphthalimide (NI) and phenothiazine (PTZ) to investigate the sequence and distance dependence of the single-step hole transfer between guanines (Gs). Hole injection into DNA was accomplished by excitation of the NI site with a 355 nm laser pulse, and the kinetics of the hole-transfer process were investigated by monitoring the transient absorption of the PTZ radical cation (PTZ.+). Kinetic analysis of the time profile of PTZ.+ based on the kinetic model showed that the distance dependence of the hole-transfer process was significantly influenced by the DNA sequence. Results of temperature- and isotope-effect experiments demonstrated that the activation energy increased as the number of bridge bases separating the Gs increased. This is because of the distance-dependent reorganization energy and contribution of the proton-transfer process to the hole transfer in DNA.
Takada
Tadao
T
The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
Kawai
Kiyohiko
K
Fujitsuka
Mamoru
M
Majima
Tetsuro
T
D004247:DNA / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D006147:Guanine / Q000737:chemistry; D007094:Imides / Q000737:chemistry; D007364:Intercalating Agents / Q000737:chemistry; D007700:Kinetics; D007834:Lasers; D009281:Naphthalenes / Q000737:chemistry; D010640:Phenothiazines / Q000737:chemistry; D011522:Protons; D013816:Thermodynamics; D014466:Ultraviolet Rays
D007094:Imides; D007364:Intercalating Agents; D009281:Naphthalenes; D010640:Phenothiazines; D011522:Protons; D006147:Guanine; D004247:DNA; C031637:phenothiazine