Peptides imaged in unprecedented detail in Radboud laser lab
Researchers from Radboud University Nijmegen and the FOM Foundation have succeeded in producing detailed 3D structures of selected peptides – the building blocks of proteins. To do this, they worked with far-infrared light produced by Radboud University Nijmegen's laser FELIX, in use since 2013. The results, published online on 27 February in Angewandte Chemie, are important for all the follow-up research on the structure elucidation of peptides and other classes of molecules.
Physical chemists study the properties of molecules using a technique in which cooled molecules, isolated from their surroundings, are radiated with infrared light of varying frequencies. The result is a unique fingerprint of the structure of the molecule – the infrared spectrum. The Nijmegen chemists also did this but, for the first time, using far-infrared light – light with a wavelength of up to 0.1 millimetres. The result was a much more detailed infrared spectrum. Angewandte Chemie highlights the publication as a very important paper and fellow researchers from all over the world are eager to work with the methods described.
Familiar peptides, new results
The free electron laser in the FELIX lab at Radboud University Nijmegen is one of the few lasers in the world capable of producing light in the far-infrared region. Anouk Rijs, assistant professor at the Department of Molecular and Biophysics in Nijmegen (before that she worked with FELIX at FOM Institute DIFFER), was responsible for the research into common peptides in the human body. Although much is already known about these peptides, important new information can now be added. "What is new about our far-infrared spectrum is that we have obtained insights in the folding of the peptides in much more detail, as well as which interactions play a role in this. This is important, for instance, for research into interactions between medicines and molecules in the body. Without far-infrared light it is not possible to obtain such detailed information about the molecular structure."
Theories inadequate
Chemists normally determine the molecular structure by comparing the measured infrared spectrum with theoretically predicted spectra. However, the new method produced so much more detail that the old theories and mathematical models were inadequate. "We therefore needed to develop new methods, which we did with colleagues from France," explains Rijs. "Using all this new information, we were able to produce an accurate 3D model of the peptides. The next step will be to study larger and more complex molecules."
FELIX and the FOM-focus group
On 14 July 2013 the free electron laser FELIX, produced its first light since the relocation from FOM institute DIFFER to Radboud University Nijmegen. The free electron lasers FELIX and FELICE were relocated to Nijmegen in April 2012 and have been assembled next to the Nijmegen laser FLARE. Together they form the international infrared and terahertz user facility FELIX, which was opened to users at the end of 2013.
In Nijmegen FELIX is part of the FOM Focus group 'Free electron lasers for infrared experiments'. The aim of the programme is to realise a leading user facility from the free electron laser FELIX and to research the structure and dynamics of complex molecules, ions and clusters in the gaseous state. Both the programme and the FOM Focus group are led by FOM focus group leader Prof.dr. Wim van der Zande.
Reference
Far-IR spectroscopy unravels gas-phase peptide structural assignments; a combination of IR-UV ion-dip experiments with BOMD simulations
Sander Jaeqx (FOM PhD student), Jos Oomens, Alvaro Cimas, Marie-Pierre Gaigeot and Anouk M. Rijs
Angewandte Chemie International Edition, 27 February 2014, DOI: 10.1002/anie.201311189 and 10.1002/ange.201311189
Information
For further information, please contact Dr. Anouk Rijs, +31 (0)24 365 39 40.