| Project/Area Number |
11680660
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Biophysics
|
|---|
| Research Institution | NARA INSTITUTE OF SCIENCE AND TECHNOLOGY |
|---|
Principal Investigator |
TMAMOTO Yasushi Nara Institute of Science and Techology, Associate Professor Graduate School of Materials Science, 物質創成科学研究科, 助教授 (80263200)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOKUNAGA Fumio Osaka University, Graduate School of Science Professor, 大学院・理学研究科, 教授 (80025452)
KATAOKA Mikio Nara Institute of Science and Technology, Graduate School of Materials Science Prefessor, 物質創成科学研究科, 教授 (30150254)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Project Status |
Completed (Fiscal Year 2000)
|
| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥2,900,000 (Direct Cost: ¥2,900,000)
|
|---|
| Keywords | protein conformational change / photocycle / Fourier transform infrared spectroscopy / water solution / hydration / amide modes / intermediates |
|---|
| Research Abstract |
Photoactive yellow protein (PYP) is a photoreceptor protein for the negative phototaxis of purple phototropic bacterium, Ectothiorhodospira halophila. On photon absorption, it undergoes the photocycle. Our X-ray scattering experiments have revealed that the large protein conformational change takes place upon formation of M intermediate as shown by the increase of the radius of gyration. However, no large changes in the vibrational amide modes, which represents the large conformational change of protein backbone, have not been detected by the previous infrared spectroscopy. In the infrared spectroscopy, to avoid a intense absorbance of water, dry sample was used. In dry samples, the flexibility of the protein is lowered and that may possibly inhibit the protein conformational change. To overcome this problem, we tried to measure the infrared absorption spectra using the PYP solution.
Using the PYP solution at high concentration (200 OD) and a thin sample cell (10 μm light path length) , the difference FTIR spectra were measured. The larger absorbance change than that in dry film was observed in amide band region. Therefore, as expected, the large conformational change takes place in the solution. Such a large conformational change was suppressed when the solvent was frozen at 253 K.This finding suggests that the protein conformational change necessary for the physiological function is suppressed in some experimental conditions.
|
