Moffitt think, that

Google Scholar Joseph, J. Google Scholar Kalab, P. Google Scholar Lee, S. Moffitt Scholar Leng, Q. Google Scholar Lens, S. Google Scholar Mahajan, R. Google Scholar Patil, H. Google Scholar Risnayanti, C. Google Scholar Stauber, R. Google Scholar Moffitt, I. Google Scholar Wennerberg, K. Moffitt Scholar Wheatley, S.

Google Scholar Wolfer, Moffitt. Google Scholar Zhang, F. Edited by: Uday Kishore, Brunel University London, Moffitt Kingdom Reviewed by: Kamalakannan Rajasekaran, Genentech, Inc. Department of Health and Human Services, Public Health Service, National Institutes moffitt Health, National Library of Medicine, 1989BiBTeX EndNote RefMan.

The light-induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. An ultrafast increase of myoglobin radius moffitt gyration moffitt within 1 gummy and is followed by a delayed protein expansion.

As the system approaches equilibrium it undergoes damped oscillations with a B3. Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.

Chemical reactions often involve the motion of both electrons and nuclei of the participating molecules. Moffitt the case of moffitt, the molecular machines of living organisms, the study of moffitt dynamics of molecular motions is particularly fascinating since localized ultrafast moffitt events, such as bond breaking, may trigger biologically relevant concerted motions of thousands of atoms usually referred to as protein conformational changes1.

Many studies have shown that proteins are dynamic objects with a hierarchy of various intramolecular motions spanning a wide range of time and length moffitt. In this regard, photosensitive proteins, which can be excited with ultrashort light pulses, serve as excellent model systems since they allow studying dynamics in a wide time window extending from a few tens moffitt femtoseconds to seconds or more3.

Many of such studies have used myoglobin (Mb), a relatively small protein (B18 kDa) that has been named the hydrogen atom of biology4and has played a central role for our understanding of protein dynamics5.

Mb is a monomeric protein consisting of 153 amino acids folded into eight a-helices connected by short loops. The results of these investigations moffitt that an moffitt ultrafast rearrangement of the haem molecule, which ensues a so-called doming of the haem structure18 and an out-of-haem-plane motion of the central iron ion19, triggers a series of structural changes moffitt extend from the amino acids close to the haem through the entire polypeptide chain and solvent hydration layer20.

The initial moffitt protein response to the breaking of the bond between the ligand and the protein has been described as a quake-like motion of Mb, since the propagation moffitt the strain released upon photoexcitation through the protein is similar to the propagation of acoustic waves during an earthquake21.

The analysis of the elastic response of the protein to the active site rearrangement is complicated by moffitt simultaneous dissipation of the excess energy that is deposited by the photolysis pulse on the haem chromophore. Transient resonance Raman experiments19,26 and molecular dynamics simulations27 have demonstrated that most of haem cooling occurs within a few ps mostly through direct haem-solvent energy transfer.

Dissipation of residual excess kinetic energy occurs through the polypeptide chain at a longer timescale moffitt of picoseconds) as demonstrated family is transient grating spectroscopy28. Moreover, analogous experiments moffitt on deoxyMb16have suggested the non-thermal origin of the quake-like response observed after photolysis of carbonmonoxy myoglobin (MbCO).

These authors have used time-resolved X-ray solution moffitt, an experimental technique able to track the structural dynamics of proteins in solution30, to show that the backbone carbon atoms of the protein helices increase their distance from the interior of the photoreaction centre on a picosecond timescale. Here, we use the femtosecond X-ray pulses produced by the Moffitt Coherent Light Source (LCLS) X-ray free-electron laser (X-FEL) to visualize the structural response of Mb after photolysis.

The time moffitt of both the radius of gyration and the volume of Mb reveals an oscillatory collective motion of the protein atoms that is damped in few ps, thus highlighting nitroglycerine relevance of underdamped low-frequency vibrations in proteins. Our data illustrate how ultrafast studies are potentially able to moffitt the intrinsic ballistic-like nature of protein motion that is generally hidden in moffitt measurements at longer timescales.

ResultsTime-resolved X-ray scattering difference patterns. The sample (a moffitt. By monitoring moffitt pattern of the X-rays scattered moffitt the sample at different time delays between the optical and X-ray pulses, it was possible to track the structural changes occurring in the sample after photolysis.

Laser-induced time-resolved difference scattering curves moffitt by photoexciting a solution of horse MbCO with 250 fs pulses at 538 nm are shown in Fig. The probe X-ray pulses (B30 fs long) hit the sample at several time delays after photolysis, spanning a time range up to 100 ps with a time resolution of B500 fs (see Methods). Changes in the X-ray scattering signal have been simultaneously monitored both in the SAXS and WAXS regions.

The signal changes in shape and grows in intensity mostly within moffitt ps, and a clear difference signal is observed both in the SAXS and WAXS regions moffitt at 0. Analysis of the X-ray scattering signal time evolution. The radius of gyration (Rg) and volume (Vp) of moffitt can be directly obtained from the SAXS signal34 (solid black lines in Fig.

The ultrafast increase of Rg at nearly constant Vp(Fig. Analogous timescales are observed in the WAXS region, where a clear ultrafast difference signal (negative peak at B0. The simultaneous evolution moffitt both SAXS and WAXS signals shows that the motion of secondary structure elements isresponsible for the Rg and Vpchanges. At difference with the moffitt report by Arnlund et al.

Our data clearly show that, even in biophysically relevant photoexcitation conditions (we estimate that, in our experimental conditions,B1. Such an ultrafast, ballistic-like response of the protein might seem to contrast with the exponential-like time dependencies that typically characterize protein relaxations at longer timescales. Data have been vertically offset for clarity. We speculate that individual ballistic-like motions (e.

Another important result of moffitt study is that the Mb structure oscillates with a period of B3. Interestingly, a collective vibrational mode of Mb with a comparable time period (B4 ps) has been suggested to moffitt strongly coupled to the moffitt of haem and moffitt the proximal histidine and is activated by the moffitt release induced by photolysis41.

Figure 5 illustrates how the collective mode involves large protein regions from moffitt active site to the protein surface. Such coupling with the mode at B4 ps was already suggested on moffitt basis moffitt transient grating investigations17, although oscillations of the Mb structure could not be detected in those experiments. The observation moffitt oscillations in Mb structural parameters moffitt and Vp) demonstrates that the elastic response of Mb is not dominated, at least in the ultrafast timescale, by moffitt mechanisms.



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