2006 Fiscal Year Final Research Report Summary
Formation of isolated DNA bases pairs and their water clusters
| Project/Area Number |
17550017
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Graduate School, Yokohama City University |
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Principal Investigator |
SAIGUSA Hiroyuki Yokohama City University, Graduate School of Arts and Sciences, Professor, 国際総合科学研究科, 教授 (90162180)
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| Co-Investigator(Kenkyū-buntansha) |
TACHIKAWA Masanori Yokonarna city Vnversity, Graduate School of Artsand Scoences, Associate Professor, 国際総合科学研究科, 教授 (00267410)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Laser Desoption / DNA bases / Hydrated clusters / Nucleosides / Tautomerization |
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| Research Abstract |
We have developed a novel laser desorption method in combination with the supersonic-jet technique for producing cold isolated clusters of the DNA bases and their hydrated clusters. This method is found to be especially effective in producing hydrated clusters of the nonvolatile molecules and thus useful in the microscopic understanding of hydration structures of DNA. The results show that excited-state dynamics of the base pairs are strongly dependent on the tautomers of the respective bases. For example, the purine base guanine reveals a tautomers of the canonical form whose excited-state lifetime is on the order of subpicosecond while other tautomers of non-canonical forms have nanosecond lifetimes. Furthermore, excited-state dynamics of adenine are altered significantly upon hydration. This is explained by the ultrafast relaxation of the initially excited state to a low-lying excited state and subsequent dissociation. This is found to be consistent with the result for 2-aminopurine in which no ultrafast dynamics occurs and thus is known to be strongly fluorescent.
We have also succeeded in producing hydrated clusters of the DNA nucleoside guanosines with high efficiency by employing this desorption technique. This is the first report of the observation of cold hydrated clusters of the nucleosides under isolated conditions. The electronic spectra of guanosines are found to be significantly red-shifted upon hydration, suggesting that the excited state-dynamics are affected by the solvation.
This laser desorption technique is expected to be effective for vaporizing thermally fragile biomolecules
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