Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantifying radiation damage in SAXS experiments

19.12.2016

Biological small-angle X-ray scattering (SAXS) is an experimental technique that provides low-resolution structural information on macromolecules. The surge of popularity of the technique is a result of recent improvements in both software and hardware, allowing for high-throughput data collection and analysis, reflected in the increasing number of dedicated SAXS beamlines such as BM29 at the ESRF, P12 at EMBL Hamburg and B21 at Diamond Light Source.

However, as for most other macromolecular structural techniques, radiation damage is still a major factor hindering the success of experiments. The high solvent proportion of biological SAXS samples means that hydroxyl, hydroperoxyl radicals and hydrated electrons are produced in abundance by the radiolysis of water when it is irradiated with X-rays. These radicals can then interact with the protein molecules, ultimately leading to protein aggregation, fragmentation or unfolding. Furthermore, molecular repulsion due to protein charging can also decrease the scattering at low angles.


SAXS envelopes of Glucose Isomerase generated from frames collected early (bottom left) and late (top right) in the experiment.

Credit: Brooks-Bartlett et al

Common methods used to reduce radiation damage to biological SAXS samples are generally concerned with limiting the X-ray exposure to any given volume of sample. In an analogous manner, cryo-cooling samples down to 100 K for SAXS (cryoSAXS) has been reported to increase the dose tolerance of SAXS samples by at least two orders of magnitude.

Applications of the above radiation damage mitigation approaches are unable to completely circumvent its detrimental effects, in particular the change of the scattering profile throughout the experiment. It is necessary to determine whether any two scattering profiles are similar so that noise can be reduced by averaging over similar curves.

For experiments by different researchers to be inter-comparable, the progression of radiation damage is most usefully tracked as a function of the dose absorbed by the sample. RADDOSE-3D is a free and open source software program used to calculate the time- and space-resolved three-dimensional distribution of the dose absorbed by a protein crystal in a macromolecular crystallography experiment; however, there is no equivalent software available for SAXS. Radiation damage studies in SAXS thus currently require the experimenters to correctly parameterize the experiment and manually calculate a single estimate of the dose within the sample.

In a paper published by Brooks-Bartlett et al. [(2017), J. Synchrotron. Rad. 24, doi:101107/S1600577516015083], extensions to RADDOSE-3D are presented, which enable the convenient calculation of doses for SAXS experiments, reducing the burden of manually performing the calculation. Additionally, the authors have created a visualisation package to assess the similarity of SAXS frames and used these tools to assess the efficacy of various radioprotectant compounds for increasing the radiation tolerance of the glucose isomerase protein sample.

Media Contact

Dr. Jonathan Agbenyega
ja@iucr.org
01-244-342-878

 @iucr

http://www.iucr.org 

Dr. Jonathan Agbenyega | EurekAlert!

Further reports about: Crystallography Quantifying SAXS damage protein molecules radicals software program

More articles from Life Sciences:

nachricht Molecular evolution: How the building blocks of life may form in space
26.04.2018 | American Institute of Physics

nachricht Multifunctional bacterial microswimmer able to deliver cargo and destroy itself
26.04.2018 | Max-Planck-Institut für Intelligente Systeme

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

World's smallest optical implantable biodevice

26.04.2018 | Power and Electrical Engineering

Molecular evolution: How the building blocks of life may form in space

26.04.2018 | Life Sciences

First Li-Fi-product with technology from Fraunhofer HHI launched in Japan

26.04.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>