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

Autor:	Shelby ML; Department of Chemistry, Northwestern University, Evanston, IL 60208., Wildman A; Department of Chemistry, University of Washington, Seattle, WA 98195., Hayes D; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60437., Mara MW; Department of Chemistry, Northwestern University, Evanston, IL 60208., Lestrange PJ; Department of Chemistry, University of Washington, Seattle, WA 98195., Cammarata M; Institut de Physique de Rennes, Université de Rennes, 35042 Rennes CEDEX, France., Balducci L; Institut de Physique de Rennes, Université de Rennes, 35042 Rennes CEDEX, France., Artamonov M; Department of Chemistry, Northwestern University, Evanston, IL 60208., Lemke HT; Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025., Zhu D; Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025., Seideman T; Department of Chemistry, Northwestern University, Evanston, IL 60208., Hoffman BM; Department of Chemistry, Northwestern University, Evanston, IL 60208; l-chen@northwestern.edu xsli@uw.edu bmh@northwestern.edu., Li X; Department of Chemistry, University of Washington, Seattle, WA 98195; l-chen@northwestern.edu xsli@uw.edu bmh@northwestern.edu., Chen LX; Department of Chemistry, Northwestern University, Evanston, IL 60208; l-chen@northwestern.edu xsli@uw.edu bmh@northwestern.edu.; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60437.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2021 Apr 06; Vol. 118 (14).
DOI:	10.1073/pnas.2018966118
Abstrakt:	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 coordinates, 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. Competing Interests: The authors declare no competing interest.
Databáze:	MEDLINE
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