| 日時: |
2004-09-06 13:30 - 14:30 |
| 場所: |
４号館２Ｆ輪講室１ |
| 会議名: |
放射光セミナー「Watching proteins function with 150-picosecond time-resolved X-ray crystallography 」 |
| 講演者: |
Dr. Philip A. Anfinrud (Laboratory of Chemical Physics/NIDDK, National Institutes of Health, USA) |
| 講演言語: |
英語 |
| URL: |
http://pfwww.kek.jp/pf-seminar/ |
| アブストラクト: |
Proteins are engaged in a myriad of tasks that are essential to life. These tasks are carried out with exquisite selectivity and efficiency, the likes of which are extremely difficult to duplicate in artificial model systems. To gain a mechanistic understanding into how proteins execute their designed function, it is crucial to know how their
structures evolve over time. We have developed the method of pico-second time-resolved macromolecular crystallography on the ID09B beam-line at the European Synchrotron and Radiation Facility, and used this technique to determine protein structures with 150-ps time resolution and < 2-? spatial resolution. We used myoglobin (Mb), a ligand-binding heme protein found in muscle, as a model system for probing protein-mediated ligand migration. In these experiments, pico-second laser pulses triggered CO dissociation from Mb and time-
delayed X-ray pulses took ＜snapshotsｃ of the protein structure. A series of snapshots were stitched together into a movie to unveil in atomic detail the correlated conformational changes that influence the rates and pathways of ligand migration. We studied both wild-type and the L29F mutant [1] of Mb. This mutation enhances the oxygen
binding affinity by about an order of magnitude, and slows its rate of auto-oxidation by a comparable amount [2]. Moreover, it accelerates the expulsion of toxic CO from the primary docking site by nearly 3 orders of magnitude. A side-by-side comparison of wild-type and L29F structural dynamics unveils the origins for the dramatically different CO migration dynamics.
References
[1] - F. Schotte, M. Lim, T.A. Jackson, A.V. Smirnov, J. Soman, J.S. Olson, G.N. Phillips, Jr., M. Wulff, and P.A. Anfinrud, Science, 300, 1944 (2003).
[2] - T. E Carver, R. E Brantley, Jr., E. W. Singleton, R. M. Arduini, M. L. Quillin, G. N. Phillips, Jr., J. S. Olson, J. Biol. Chem. 267, 14443 (1992).
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