Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Filming an ultra-fast biological reaction essential to life

25.06.2003


Migration of the CO after photolysis. The sites that are currently occupied by the CO are marked by solid yellow circles. Sites from which the CO has departed are depicted by a dotted yellow circle


A team of scientists from the USA in collaboration with staff at the European Synchrotron Radiation Facility (Schotte et al) have managed to film a protein at work in unprecedented detail. The protein is the oxygen-storing molecule myoglobin, which plays a central role in the production of energy in muscles. The motion of the protein was recorded using ultra-short flashes of X-ray light from the synchrotron. The new insight in the functionality of myoglobin has led to a deeper understanding of the molecular processes associated with respiration. An article on the subject was published Friday 20 June in "Science" under the title Watching a Protein as it Functions with 150-ps Time-Resolved X-ray Crystallography.

Every time we contract a muscle, myoglobin releases oxygen which is used by all mammals for the production of energy. Muscle cells use myoglobin as a peak-load buffer when blood cannot supply oxygen fast enough, for example when the circulation is blocked during muscle contraction. The oxygen molecule is initially confined in a cavity called the heme-pocket, where it is chemically bound to an iron atom.

The three-dimensional pictures taken at the ESRF resolve positions of all the 1432 atoms in the protein, and pinpoint how the carbon monoxide (CO) molecule – used here as a replacement for oxygen (O2) for technical reasons - literally finds its way out of the very dense atomic structure near the iron atom. The scientists have discovered that the CO molecule does not move out smoothly; in fact it spends most of its time captured in 5 tiny cavities inside the protein. In the first cavity near the iron atom, the CO molecule makes an extremely brief visit lasting only 100 picoseconds2, i.e. a tenth of a billionth of a second. Iron would naturally try to rebind CO, but nearby molecules block the CO from going back to the iron. The film has shown that the motion between the 5 cavities is very fast. The CO molecule reaches the fifth cavity after 30 nanoseconds and then it disappears into the solvent surrounding the protein. The interesting thing is that eventually another CO molecule, released from a myoglobin molecule nearby, will diffuse back towards the iron, most likely through another route. The iron accepts the incoming CO due to the fact that the structure of the protein has changed to allow for the rebinding.



Watching myoglobin as it functions is more complicated than it may seem. First of all, the scientists have to control the start of the experiment extremely precisely. The experiment begins by the injection of a flash of laser light to perturb the molecules and release the CO molecule inside the protein. Very shortly afterwards, they expose the protein crystal to an intense flash of X-rays. The X-rays are scattered by the protein into diffraction3 pictures that are later analysed by computers. The duration of an X-ray flash from the synchrotron is as short as 100 picoseconds and that is in principle the shortest time duration that can be investigated at the ESRF.

About the “scenario” for the filming

The live filming of the protein took place in ID09, one of the 40 beamlines at the ESRF. A beamline is a laboratory for X-ray studies. The X-ray radiation enters the experimental cabin and “shoots” on a sample, in this case, a crystallised protein. This beamline, called White Beam Station, is a beamline designed for time-resolved experiments in macromolecular crystallography and liquids, and also for high pressure research. Its unique feature is the focused white beam, which can be used for time-resolved diffraction on macromolecules.

Montserrat Capellas | alfa
Further information:
http://www.esrf.fr/News/FrontNews/PressRelease_23-06-2003/

More articles from Interdisciplinary Research:

nachricht NRL clarifies valley polarization for electronic and optoelectronic technologies
20.10.2017 | Naval Research Laboratory

nachricht Integrated lab-on-a-chip uses smartphone to quickly detect multiple pathogens
19.10.2017 | University of Illinois College of Engineering

All articles from Interdisciplinary Research >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Taming 'wild' electrons in graphene

23.10.2017 | Physics and Astronomy

Mountain glaciers shrinking across the West

23.10.2017 | Earth Sciences

Scientists track ovarian cancers to site of origin: Fallopian tubes

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>