| Project/Area Number |
11554028
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
機能・物性・材料
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| Research Institution | JAPAN ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY |
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Principal Investigator |
YOSHIHARA Keitaro JAPAN ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY, Professor, 材料科学研究科, 副学長 (40087507)
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| Co-Investigator(Kenkyū-buntansha) |
RUTKOVSKI Pavel 東京インスツルメンツ(株), 計測部, 主任研究員
KUMAZAKI Shigeichi JAPAN ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY, Research Associate, 材料科学研究科, 助手 (40293401)
AONO Shigetoshi JAPAN ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY, Associate Professor, 材料科学研究科, 助教授 (60183729)
RUBTSOV Igor
RUBTSOV Igor V. 北陸先端科学技術大学院大学, 材料科学研究科, 助手 (70293404)
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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 |
¥10,700,000 (Direct Cost: ¥10,700,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥8,100,000 (Direct Cost: ¥8,100,000)
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| Keywords | FEMTOSECOND / TIM-RESOLVED INFRARED SPECTROSCOPY / IR SHORT PULSE / CARBON MONOXIDE / CooA / TRANSCRIPTION / PROTEIN DYNAMICS / CooA / フェムト秒 / 赤外分光システム / 道伝信号伝達分子 / 遺伝転写制御 / 一般化炭素 / タンパク構造変化 / フェムト秒赤外分光 / 分子構造動力学 / ヘムタンパク / 遺伝伝達信号分子 |
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| Research Abstract |
The design and performance of a femtosecond time-resolved mid-infrared transient absorption spectrometer is illustrated. The spectrometer was developed from a set of commercially available Ti : sapphire femtosecond lasers utilizing difference frequency mixing technique. With this spectrometer, the transient absorption in the mid-infrared region from 800 to 2800 cm^<-1> was detected with a sensitivity of 1×10^<-4> for difference absorbance at a repetition rate of 1 kHz. With a sub-picosecond visible or ultraviolet pump, a time-resolution of 250fs has been obtained. A study on the binding and dissociation processes of carbon monoxide in myoglobin is presented as an example of its applications.
CooA, which is a transcriptional regulator heme protein allosterially triggered by CO, is studied by femtosecond visible-pump mid-IR-probe spectroscopy. Transient bleaching upon excitation of the heme into Soret band is detected at around 1979cm^<-1>, which is the absorption region of the CO bound to the heme. The bleach signal shows a nonexponential decay with time constants of 56 ps and 290 ps, caused by the rebinding of the CO to the heme. About 97% of dissociated CO recombines geminately. The geminate recombination rate in CooA is significantly faster than that in myoglobin and hemoglobin. The angle of the bound CO with respect to the porphyrin plane is calculated to be about 78 degrees based on the anisotropy measurements. A shift of the bleach mid-IR spectrum of the bound CO is detected having characteristic time of 160 ps. It is suggested that the spectral shift is caused by a difference in the frequency of the bound CO in different protein conformations, particularly in active conformation and in intermediate one. Thus, the biologically relevant conformation change in CooA was traced. Possible assignment of the observed conformation change is discussed.
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