| Project/Area Number |
11640495
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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 | Institute for Chemical Reaction Science, Tohoku University |
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Principal Investigator |
OHBA Yasunori Tohoku University, Institute for Chemical Reacton Science, Associated Professor, 反応化学研究所, 助教授 (10176985)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | electron paramagnetic resonance / electron spin resonance / nutation spectrum / heme protein / myoblobin / pulsed EPR / 電子常時性共鳴 |
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| Research Abstract |
A new technique of two-dimensional nutation spectroscopy for a disordered system with large g-anisotropy was developed. This method is based on the fact that a nutational frequency is determined by the g value which belongs to the direction perpendicular to the external magnetic field. The method enables one to determine a very small g-value (typically less than 1) and relative sign of g-principal values. The method is applied to low-spin met myoglobin from horse heart.
1. The most important part of the pulsed EPR instrument for the nutational experiment is the microwave resonator. A strong and homogeneous microwave field is essential. A loop-gap resonator was compared with a rectangular cavity resonator. A stable sample holder of a loop-gap resonator for helium temperature measurements was designed and constructed.
2. A nutation signal from a disordered sample was analyzed by a spectral simulation technique. A gated integration and ESE-FT methods were compared as a detection technique. The analysis showed that there was some distortion and shift of a spectrum in a gated integration caused by off-resonance effects. These artifacts could be removed by the ESE-FT technique.
3. Two-dimensional nutation spectra were observed for low-spin horse heart met-myoglobin in frozen solution. By means of the ESE-FT technique, the nutation spectra those were free from off-resonance effects were obtained. The spectra were compared with theoretical predictions for magnetic field dependence of a nutational spectrum. It is confirmed that a nutation frequency was determined by the g-principal value of the direction orthogonal to the external magnetic field. The very small g-value of cyanide ion complex, g=0.93, could be observed by this method.
4. It was predicted by the theoretical analysis that relative sign of g-principal values could be determined by a nutation spectrum from a disordered system.
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