Biochemistry: New technique to study interaction of metal ions in a liquid

Sep 19, 2012 by Anaïs Schaeffer
In the heart of the LOI88 experiment: this is the point where the metal ions (from the left) enter the drop. 

In August, the members of an ISOLDE project called LOI88 successfully employed a new technique to study the interaction of metal ions in a liquid. It's the first time that specific ions have been studied in a liquid medium - a technical achievement that opens promising doors for biochemistry.

"More than half of the proteins in the human body contain metal ions such as magnesium, zinc and copper," explains Monika Stachura, a biophysicist at the University of Copenhagen and the LOI88 project leader. "We know that these elements are crucial to a protein's structure and function but their behaviour and interactions are not known in detail." Detecting these ions directly in  a body-like environment is problematic as their closed atomic shells make them invisible to most . However, using the beta- (β-NMR) technique in combination with the COLLAPS beamline the LOI88 team succeeded, for the first time, in recording a signal from metal ions in a body-like environment. This also proves that basic nuclear physics research and techniques can lead to novel applications.

To obtain these excellent results, the team first had to meet a challenge: to find a way to introduce "easily visible" metal ions into a liquid, in order to then "see" their signal. And by "visible", ISOLDE of course mean "radioactive". Their choice: radioactive magnesium 31 ions (31Mg++). The technique: β-NMR. The setup: complicated…

"First of all, we needed a Mg31 from ISOLDE," says Magdalena Kowalska, a β-NMR physicist participating in the project and the ISOLDE physics coordinator. "As we are using the NMR technique, we have to polarize the spins of these ions, which is done using from the ISOLDE-COLLAPS set-up. The polarized ions are then caught by a drop of the liquid." Sounds easy? Not if you consider that the beam has to stay in a vacuum, but the liquid cannot. "When a  is placed in a vacuum it first boils and then freezes, making it impossible to perform the experiment," explains Alexander Gottberg, an ISOLDE target physicist from CSIC, Madrid, who designed the experimental set-up. "To overcome the problem, we had to introduce a pressure difference between the weak vacuum around the liquid target and the high vacuum in the beamline. The most challenging part of this design was that the differential pumping system, which was used for this purpose, had to be hosted on just a few centimeters."

A falling drop during the measurements.

Mg31 has a half-life of only 230 ms so, in less than a second, physicists can observe it decaying in the drop of liquid. And it's precisely this decay that gives the long-sought information. "By decaying, Mg31 emits beta particles," explains Magdalena. "As we polarized the Mg31 ions, this emission of beta particles isn't the same in all directions: we call this an 'anisotropy'." In simple words, scientists detect a different number of beta particles on "the left" detector than on "the right" one.

But what does this anisotropy mean? "From our theoretical models, we can deduce the interactions of the metal ions in the liquid by looking at the NMR radiofrequency that cancels the anisotropy," explains  Alexander.

"By proving the feasibility of the technique, we have opened new doors for biochemistry," concludes Monika. "We are now preparing the next steps: injecting macromolecules and later proteins into the liquid to see how interact with them." The three experts confided that they were "extremely excited". No kidding!

Explore further: Could 'Jedi Putter' be the force golfers need?

add to favorites email to friend print save as pdf

Related Stories

Aqueous iron interacts as strong as solid iron

Jul 06, 2012

German scientists have applied a new method -- "inverse Partial Fluorescence Yield" (iPFY) on micro-jet -- which will enable them to probe the electronic structure of liquids free of sample damages. The experiments ...

Getting positive results with negative ions

Jul 18, 2011

Yes! That's the answer scientists from OI Analytical and Pacific Northwest National Laboratory got from their experiments to see if the new IonCCDTM can detect negative ions and large ions. Furthermore, employing ...

New territory in nuclear fission explored with ISOLDE

Jan 17, 2011

An international collaboration led by the University of Leuven, Belgium, exploiting ISOLDE’s radioactive beams, has recently discovered an unexpected new type of asymmetric nuclear fission, which challenges ...

A Venus flytrap for nuclear waste

Jan 26, 2010

Not every object is food to a Venus flytrap. Like the carnivorous plant, a new material developed at Northwestern University permanently traps only its desired prey, the radioactive ion cesium, and not other harmless ions ...

Recommended for you

Could 'Jedi Putter' be the force golfers need?

Apr 18, 2014

Putting is arguably the most important skill in golf; in fact, it's been described as a game within a game. Now a team of Rice engineering students has devised a training putter that offers golfers audio, ...

Better thermal-imaging lens from waste sulfur

Apr 17, 2014

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

User comments : 0

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...