Dynamics of ultraviolet-induced DNA lesions: Dewar formation guided by pre-tension induced by the backbone

被引：23

作者：

Fingerhut, B. P.

Herzog, T. T. ^{[2
]}

Ryseck, G. ^{[2
,3
]}

Haiser, K. ^{[2
]}

Graupner, F. F. ^{[2
]}

Heil, K. ^{[1
]}

Gilch, P. ^{[2
,3
]}

Schreier, W. J. ^{[2
]}

Carell, T. ^{[1
]}

de Vivie-Riedle, R. ^{[1
]}

Zinth, W. ^{[2
]}

机构：

[1] Univ Munich, Dept Chem, Ctr Integrat Prot Sci, D-81377 Munich, Germany

[2] Univ Munich, Fac Phys, Ctr Integrat Prot Sci, D-80538 Munich, Germany

[3] Univ Dusseldorf, Inst Phys Chem, D-40225 Dusseldorf, Germany

来源：

NEW JOURNAL OF PHYSICS | 2012年 / 14卷

关键词：

EXCITED-STATE DYNAMICS; CYCLOBUTANE PYRIMIDINE DIMERS; ULTRAFAST INTERNAL-CONVERSION; CONICAL INTERSECTIONS; THYMINE DIMERIZATION; CRYSTAL-STRUCTURE; ENERGY SURFACES; TRIPLET-STATE; AB-INITIO; FLUORESCENCE;

D O I：

10.1088/1367-2630/14/6/065006

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

The photophysical and photochemical processes driving the formation of the ultraviolet (UV)-induced DNA Dewar lesion from the T(6-4) T dimer are investigated by time-resolved spectroscopy and quantum chemical modelling. Time-resolved absorption and emission spectroscopy in the UV revealed a biexponential decay of the electronically excited state (S-1) with time constants in the 100 ps and 1 ns range. From the S-1 state the system forms the Dewar lesion (proven by time-resolved infrared spectroscopy), the triplet state of the T(6-4) T dimer and the ground state of the original T(6-4) T dimer. The decay process from the excited singlet is activated and thus temperature dependent. Quantum chemical modelling is used to describe the reaction path via a minimum on the excited electronic potential energy surface in close proximity to a triplet state. The transition to the Dewar isomer competes with internal conversion and with triplet formation. Only if the backbone between the two thymines is closed, is the Dewar isomer formed with a significant yield. The simulations reveal that the tension built up by the backbone is required for guiding the reaction to the conical intersection leading to the Dewar isomer.

引用

页数：25

共 67 条

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