| DATE: |
2013-04-12 13:30 - 15:30 |
| PLACE: |
#1 meeting room, 2nd floor, 4 go kan - #324 Tokai 1go kan |
| TITLE: |
IMSS seminar (13-02) Dynamic Crystallography with Time Resolution from Infinity to Sub-X-ray-bunch |
| CONTACT: |
Shin-ichi Adachi 4737 |
| SPEAKER: |
Dr. Zhong Ren (Center for Advanced Radiation Sources, The University of Chicago) |
| ABSTRACT: |
In this post genomics era, protein crystallography is gaining an extra dimension as it develops into dynamic crystallography. Along this dimension, a desired control parameter is varied to initiate a reaction, to stimulate a response, or to perturb a structure from its steady state. In the meanwhile, a sequence of ever-evolving structures is monitored to gain mechanistic insights into the working machinery of a protein. Although this is very much a forward-looking description of protein crystallography in the foreseeable future, a few recent examples have already strived to move in the right direction. Some of the chief difficulties have been overcome; others are being worked on. Nearly 300 tetrameric hemoglobin structures are accumulated in the Protein Data Bank (PDB) since the conception of protein crystallography. Although none of these static structures is associated with an experimental time resolution, the entire collection encapsulates functional dynamics along an extensive reaction pathway.
I will discuss a meta-analysis of PDB that results in a reverse engineered cooperative mechanical device. Time-resolved experiments with ultrafast time resolution aim at filling the gap revealed by the meta-analysis. The experimental time resolution of 100 ps limited by the pulse length of a circular synchrotron X-ray source is challenged by a new strategy of placing a much shorter laser pump pulse within the X-ray probe pulse. I will also demonstrate that an asymmetric state of an invertebrate hemoglobin communicates structural signal for cooperative oxygen binding, and the ultrafast structural responses to ligand photodissociation that lead towards the crucial intermediate state.
[references]
(1) Z. Ren, P.W.Y. Chan, K. Moffat, E.F. Pai, W.E. Royer Jr., V.
Šrajer & X. Yang,
Resolution of structural heterogeneity in dynamic crystallography,
Acta Cryst. D,
in press, 2013.
(2) Z. Ren, V. Šrajer, J.E. Knapp & W.E. Royer, Cooperative
macromolecular device
revealed by meta-analysis of static and time-resolved structures,
Proc. Natl. Acad.
Sci. USA 109, 107-112, 2012.
(3) X. Yang, Z. Ren, J. Kuk & K. Moffat, Temperature-scan cryocrystallography
reveals reaction intermediates in bacteriophytochrome, Nature 479, 428-432,
2011.
(4) T. Graber, P. Anfinrud, H. Brewer, Y.-S. Chen, H.-S. Cho, N. Dashdorj, R.W.
Henning, I. Kosheleva, G. Macha, M. Meron, R. Pahl, Z. Ren, S. Ruan, F.
Schotte, V. Šrajer, P.J. Viccaro, F. Westferro & K. Moffat, BioCARS: a
synchrotron resource for time-resolved X-ray science, J. Synchrotron Rad. 18,
658-670, 2011. |
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