| Project/Area Number |
62460238
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
生物物性学
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| Research Institution | Tokai University |
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Principal Investigator |
MASHIMO Satoru Department of Physics, Tokai University, 理学部, 教授 (80056283)
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| Co-Investigator(Kenkyū-buntansha) |
YAGIHARA Shin Department of Communications Engineering, Tokai University Junior College, 東京短大, 講師 (40191093)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Keywords | Transition from B- to A-DNA / Transition from B-, Z- to A-DNA / Dielectric relaxation spectrum / TDR / 結合水 / B型DNA / DNAのほつれ |
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| Research Abstract |
Recent development of time domain spectroscopy is remarkable. Numerical fourier transform of a response function can be preformed fast and easily by using a microcomputer. In this work a step voltage pulse with 200mV height and 35pa rise time is applied to sample through 50 coaxial line and reflected wave measured in the time domain is fourier transformed to give a complex permittivity over a wide frequency region 10^6-10^<10> Hz. We found by this new technique that every biomaterials including living organisms exhibit a relaxation peak around 100MHz irrespectively of 20GHz peak due to bulk water. The 100MHz peak was concluded to be due to bound water.
In solution of DNA in SSC buffer too, the 100MHz peak was observed clearly irrespectively of bulk water peak. The 100MHz peak shows a clear transition like order-disorder transition at the denaturation temperature. On the DNA surface in double helix water molecules construct string like multimers or two dimensional network structure. On t
… More
he other hand, in the case of DNA above the denaturation temperature, bound water cannot construct such ordered cluster like stringlike multimer on the polymer chain. Bound water structure is thus very sensitive to DNA structure. Calf thymus DNA shows a transition B<double arrow>A in water-ethanol mixture with appropriate buffer. Bound water relaxation exhibits also a transition according to the structural transition. In order to keep B-form, twenty water molecules, at least, must be bond to one nucleotide. If the molecules are removed by same means, B-DNA is transformed into A-DNA. DNA analogy of poly(dG-dC)poly(dG-dC) shows transition B<double arrow>Z<double arrow>A in water-ethanol mixtures. If bound water to phosphate is exclusively removed from B-DNA B Z transition takes place. Z-DNA has only a half of bound water compared to B-DNA. A-DNA has about fifteen water molecules. The bound water relaxation observed in tropocollagen was indicated first that the bound water structure is essentially stringlike multimer. Further investigations on biomateriasl such as globular protein and biomembrane will make clear the role and function of the bound water. Less
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