4.8 Article

Interplays of electron and nuclear motions along CO dissociation trajectory in myoglobin revealed by ultrafast X-rays and quantum dynamics calculations

出版社

NATL ACAD SCIENCES
DOI: 10.1073/pnas.2018966118

关键词

protein structural dynamics; myoglobin; X-ray transient absorption; time-resolved solution X-ray scattering; quantum dynamics calculation

资金

  1. Ultrafast Initiative (theoretical work) of the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, through Argonne National Laboratory [DE-AC02-06CH11357]
  2. NIH [R01-GM115761, R01-HL63203]
  3. US DOE, Office of Science, Office of Basic Energy Sciences [DEAC02-76SF00515]
  4. DOE Computational and Theoretical Chemistry grant [DE-SC0006863]
  5. state of Washington through the University of Washington Clean Energy Institute
  6. National Institute of General Medical Sciences of NIH [5T32 GM008382, 5R01GM111097]
  7. US DOE, Atomic, Molecular Optical Science Program [DE-FG02-04ER15612/0013]
  8. Joseph J. Katz Fellowship from Argonne National Laboratory
  9. CNRS [Projets Exploratoires Premier Soutien Soutien aux Activites Scientifiques Francaises autour des Lasers a Electrons Libres Emettant des Rayons X (PEPS SASLELX)]
  10. European Union [637295]
  11. Student Technology Fee
  12. Marie Curie Actions (MSCA) [637295] Funding Source: Marie Curie Actions (MSCA)

向作者/读者索取更多资源

The study focused on ultrafast structural dynamics during the photodissociation of carbon monoxide from iron(II)-heme in bovine myoglobin. Experimental and computational results revealed insights into the interplay between nuclear and electronic structural dynamics. Additionally, the observation of protein quake caused by CO dissociation provides important implications for understanding gas transport and protein deligation processes.
Ultrafast structural dynamics with different spatial and temporal scales were investigated during photodissociation of carbon monoxide (CO) from iron(II)-heme in bovine myoglobin during the first 3 ps following laser excitation. We used simultaneous X-ray transient absorption (XTA) spectroscopy and X-ray transient solution scattering (XSS) at an X-ray free electron laser source with a time resolution of 80 fs. Kinetic traces at different characteristic X-ray energies were collected to give a global picture of the multistep pathway in the photodissociation of CO from heme. In order to extract the reaction coordinates along different directions of the CO departure, XTA data were collected with parallel and perpendicular relative polarizations of the laser pump and X-ray probe pulse to isolate the contributions of electronic spin state transition, bond breaking, and heme macrocycle nuclear relaxation. The time evolution of the iron K-edge X-ray absorption near edge structure (XANES) features along the two major photochemical reaction co-ordinates, i.e., the iron(II)-CO bond elongation and the heme macrocycle doming relaxation were modeled by time-dependent density functional theory calculations. Combined results from the experiments and computations reveal insight into interplays between the nuclear and electronic structural dynamics along the CO photodissociation trajectory. Time-resolved small-angle X-ray scattering data during the same process are also simultaneously collected, which show that the local CO dissociation causes a protein quake propagating on different spatial and temporal scales. These studies are important for understanding gas transport and protein deligation processes and shed light on the interplay of active site conformational changes and large-scale protein reorganization.

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