Method development advance at the University of Bonn allows deeper insight into cellular processes
Scientists at the University of Bonn have succeeded in observing an important cell protein at work. To do this, they used a method that allows to measure structural changes within complex molecules. The further developed procedure makes it possible to elucidate such processes in the cell, i.e. in the natural environment. The researchers are also providing a tool kit, which allows a wide range of molecules to be measured. Their study has now been published in the journal "Angewandte Chemie International Edition".
If we want to open a Christmas season walnut, we usually use a nutcracker. In the simplest case, this consists of two arms, which move against each other around a joint and can thus exert pressure on the shell. Very simple, actually - to understand how this kind of nutcracker works, it is sufficient for us to see it in action just once.
However, it is much more difficult to understand how cellular molecules work. They also alter their spatial structure as they work - similar to the nutcracker, where the arms open or close. These conformational changes tell experts a great deal about the way in which the molecule fulfills its job. Unfortunately, it is very difficult to measure these kind of movements because they occur on a very small length scale. This applies even more so if one wants to investigate the structural changes in the natural cellular environment, where countless simultaneous processes make it very hard to isolate any specific information from the general noise.
The working group from the Institute for Physical and Theoretical Chemistry at the University of Bonn has now succeeded in doing this. To this end, the scientists further developed a method that has been used for many years to measure distances within large molecules. "However, this normally only works in a test tube," explains the head of the study, Prof. Olav Schiemann. "In contrast, our technique can also be used in cells."
The researchers used what is known as electron paramagnetic resonance spectroscopy (EPR) for their measurements. The molecule to be measured is usually given a magnetic marker at two different sites. Through radiation with microwaves, the polarity of one of these mini magnets is reversed. The magnetic field emitted by it is thus changed, which in turn influences the second mini magnet. This influence is greater the closer both markers are to each other.
"We now measure how strongly the second magnet reacts to the reverse polarity of the first," explains Schiemann. "From this, we can ascertain the distance between both markers." If - metaphorically speaking - both arms of the nutcracker are marked in this way, their movement against each other can be understood.
Magnetic ruler measurements
In principle, the technique is not new. "However, we have succeeded in producing a new kind of label with which we can mark a wide range of biomolecules in a site-specific way", explains Schiemann's staff member Jean Jacques Jassoy. Usually, these labels consist of radicals - which are chemical compounds that carry a single free electron. The electron acts as a magnet during the measurement. The problem here: single electrons are highly reactive - they try to form pairs of electrons as quickly as possible. The chemists at the University of Bonn thus used a very stable radical in their work - a so called trityl group. They created various derivatives of this trityl radical. Each of these magnetic markers is designed to target specific sites within biomolecules and thus enables several approaches for the structural analysis of different biomolecules.
In their study, the researchers used this methodological advance to investigate a protein from the cytochrome P450 group. These proteins occur in almost all living beings and fulfill important tasks, for instance during oxidation processes in the cell. "With our method, we were able to precisely measure the distance between two areas of the cytochrome to a fraction of a millionth of a millimeter," emphasizes Schiemann´s staff member Andreas Berndhäuser.
The procedure is suitable for making biomolecule conformational changes visible in the cell. At the same time, it also generally facilitates the clarification of molecular structures. Schiemann: "We are thus providing researchers with a new tool kit that could help answer many biochemical questions."
Publication: J. Jacques Jassoy, Andreas Berndhäuser, Fraser Duthie, Sebastian P. Kühn, Gregor Hagelueken, Olav Schiemann: Versatile Trityl Spin Labels for Nanometer Distance Measurements on Biomolecules in vitro and within cells; Angewandte Chemie International Edition; DOI: 10.1002/anie.201609085
Olav Schiemann | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences