Dear ifeffit mailing list recipients,
See seminar details below, and please send recommendations for speakers.
Jerry Seidler (seidler@uw.edu)
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*Deciphering the Dynamics of the Ferrous Cytochrome c Photodissociative
State Using Ultrafast X-ray Spectroscopy and Scattering Methods*
Prof. Michael Mara (Northwestern University)
Thursday August 26: 9 am Seattle (PDT), 12 noon NY, 5 pm London, 6 pm
Berlin, 7 pm Moscow
link: https://washington.zoom.us/j/92742942089
password: EXAFS
*Abstract*: The femtosecond X-ray pulses provided by X-ray free electron
lasers enable tracking of electronic and structural dynamics in
metalloprotein active sites immediately following photoexcitation. Here, we
decipher the evolution of the photodissociated state of ferrous cytochrome
c using Fe K-edge X-ray absorption and emission spectroscopies, as well as
X-ray solution scattering. By absorption and emission methods, we track the
rebinding of the cleaved ligand and identify an electronic intermediate
state involved in ligand dissociation. X-ray scattering further defines the
early-time active site structure while following heat dissipation from the
hot ground state of the active site into the solvent. By relating the
active site temperature to the kinetics of ligand recombination, we
quantify the protein bulk contribution to stabilizing the protein
iron-methionine bond; this is the first direct measurement of the protein
entatic state, whereby the protein regulates activity through modest tuning
of the energetics of the active site.
*Suggested reading:*
[1] Mara, M. W. et al., Metalloprotein entatic control of ligand-metal
bonds quantified by ultrafast x-ray spectroscopy, Science, 2017, 356,
1276-1280. https://science.sciencemag.org/content/356/6344/1276.full
[2] Reinhard, M. E. et al, Short-lived metal-centered excited state
initiates iron-methionine photodissociation in ferrous cytochrome c, Nature
Communications, 2021, 12, 1086. https://doi.org/10.1038/s41467-021-21423-w
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*Gerald Seidler*
*Professor, Physics Department*
*University of Washington*
*http://faculty.washington.edu/seidler/index.html
http://faculty.washington.edu/seidler/index.html*
*seidler@uw.edu