We report time-resolved X-ray absorption measurements after photolysis of carbonmonoxy myoglobin performed at the LCLS X-ray free electron laser with nearly 100 fs (FWHM) time resolution. Data at the Fe K-edge reveal that the photoinduced structural changes at the heme occur in two steps, with a faster (∼70 fs) relaxation preceding a slower (∼400 fs) one. We tentatively attribute the first relaxation to a structural rearrangement induced by photolysis involving essentially only the heme chromophore and the second relaxation to a residual Fe motion out of the heme plane that is coupled to the displacement of myoglobin F-helix.
Levantino, M., Lemke, H., Schirò, G., Glownia, M., Cupane, A., Cammarata, M. (2015). Observing heme doming in myoglobin with femtosecond X-ray absorption spectroscopy. STRUCTURAL DYNAMICS, 2(4) [10.1063/1.4921907].
Observing heme doming in myoglobin with femtosecond X-ray absorption spectroscopy
LEVANTINO, Matteo;CUPANE, Antonio;
2015-01-01
Abstract
We report time-resolved X-ray absorption measurements after photolysis of carbonmonoxy myoglobin performed at the LCLS X-ray free electron laser with nearly 100 fs (FWHM) time resolution. Data at the Fe K-edge reveal that the photoinduced structural changes at the heme occur in two steps, with a faster (∼70 fs) relaxation preceding a slower (∼400 fs) one. We tentatively attribute the first relaxation to a structural rearrangement induced by photolysis involving essentially only the heme chromophore and the second relaxation to a residual Fe motion out of the heme plane that is coupled to the displacement of myoglobin F-helix.
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