| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Irradiation of UV light on DNA causes photoreactions of pyrimidine bases.Thymine compounds in solution gives four kinds of photodimer.Photodimerization of thymine in DNA, however, afford only one isomer, cis-syn photodimer.This reason is that orientation of thymine bases in DNA is controlled by base pairing with.The object of this project is a simulation of the photodimerzation of thymine in DNA, and application to high-density reversible photorecording system.
At first, photodimerization reactions poly T were investigated in solution in the presence or absence of poly A.Increase of the reactivity of poly T for photodimerization was observed in the presence of poly A.The result indicated that controlled orientation of thymine caused an acceleration of the photodimerization reaction.
In order to apply the photodimerization of thymine to the photorecording system, the photoreaction in solid state should be studied.Then, the photodimerization of the thymine derivatives was studied in solid
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film and single crystals.From the results of the photodimerization of 1-alkylthymine in single crystal, the photodimerization of thymine was found to be occurred by disrotatory motion in crystal.In addition to the orientation, mobility of thymine bases for rotation was found to be another important factor for the photodimerization of thymine in solid state.
Among the four photodimers of thymine, cis-syn photodimer gives easily the original thymine by irradiation at 240 nm.This fact indicates that complete reversible photodimerization can be achieved by the thymine derivative which gives only cis-syn photodimer.
Cyclic bis-thymine compounds were prepared and the photodimerization reaction was studied in this project.In this compound, two thymine bases are linked by two propyl groups.Photodimerization of the cyclic bis-thymine compound gave only cis-syn photodimer.Reversibility of the photodimerization was found to be complete.This result is to be expected for a high-density reversible photorecording system. Less
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